Mini Store - Heat Geek / Newark Cylinders for ASHP

[SteamyTea]

On 18/06/2024 at 07:39, JohnMo said:

Not really re inventing, just a variation, like spoked becoming alloy wheels. Does the same thing packaging slightly different.

Not sure that is a good analogy as wheel rims, once fitted to a vehicle, hang from spokes, while a solid cast wheel distributes the loads through all the 'spokes' (loads vary with the angle, but they can cope with tension, compression and shear forces, traditional spokes can only handle tension).

[SteamyTea]

On 18/06/2024 at 06:52, Dave Jones said:

they are re-inventing the wheel.

 

We use a bog standard cylinder with an external plate heat exchanger. Heats 300L tank to 50c in less than 30 mins. Can also daisy chain more cheap cylinders as required for capacity.

I seem to remember you saying that with all heat pump systems means you will run out of hot water and the only solution was a gas combi boiler.

What has changed your mind?

[JamesPa]

2 minutes ago, SteamyTea said:

We use a bog standard cylinder with an external plate heat exchanger. Heats 300L tank to 50c in less than 30 mins. Can also daisy chain more cheap cylinders as required for capacity.

If you have the space and an easy route for the G3 drain.  'Best' depends on the circumstances, there is no right answer, the market is big enough and the product simple enough to support a variety of solutions optimised for different users and circumstances.

[SteamyTea]

@JamesPa

You seem to have quoted my quote from @Dave Jones

 

But I agree, there are many solutions.

[Beelbeebub]

I think Heatpumps are inherently incapable of continuous DHW production in a gas boiler fashion. 

 

The 2 points are the power demand of instantaneous DHW production - typically 20kw and more - vs the typical maximum heating load means you end up massively oversizing for what is a small% of the use time. 

 

Unlike gas boilers, the peak power output of a HP is proportional to the size of the unit. A 40lw gas boiler isn't much bigger than a 12kw one. The mass of metal, plastic etc aren't much bigger.  So whilst a gas boiler can be oversized easily and cheaply, you pay a much higher upfront cost for a bigger HP. 

 

The second point is that there are times of year when a HP will need to defrost. This means the HP cannot guarentee to always supply hot water. With heating, the 10 minute pause to defrost is unimportant. With instantaneous DHW production it is a deal breaker. 

 

 

Thats not to say that we cannot have a sensible amount of hat water availble with a quick recovery time that gives an identical experience to a combi 99% of the time. 

[JohnMo]

15 minutes ago, Beelbeebub said:

second point is that there are times of year when a HP will need to defrost

My heat pump explicitly does not defrost during DHW production - it can't be the only one.  My worry would be another condition of the heat pump, is if it doesn't hit DHW target before it gets 60, it cuts back DHW target 10 degs, each time.

 

Plus - It looks like they have only tested on a Vaillant ASHP.

[Beelbeebub]

13 hours ago, JohnMo said:

My heat pump explicitly does not defrost during DHW production - it can't be the only one.  My worry would be another condition of the heat pump, is if it doesn't hit DHW target before it gets 60, it cuts back DHW target 10 degs, each time.

 

Plus - It looks like they have only tested on a Vaillant ASHP.

But it's DHW cycle is limited. 

 

For true combi performance we need to produce hot water for an infinite time. If you don't defrost you HP the capacity and efficency drop (which is why we do defrost them). That will eventually mean the amount of hot water you can instantaneously heat will fall and your bath or shower will become tepid.. You already get this if you have to many hot water draws on a combi. If someone is showering and someone else fills the bath, the flow rate and temp fall. 

 

What people really want for a "just like a combi" heat pump is an installation that takes up similar internal room to a gas boiler. 

 

As HG identified the issue is more the storage of hot water. Current approach is a large UV cylinder. This is OK if replacing a large UV cylinder but when you are swapping a vented cylinder you get the g3 issues and when you are swapping a combi you get the G3 and space issues. 

 

A combi or at most,. Kitchen unit or kitchen cupboard hot water storage and delivery system that could operate efficiently on a HP (ie no high temp bricks or phase change) woiod be very useful. 

[JamesPa]

9 hours ago, Beelbeebub said:

A combi or at most,. Kitchen unit or kitchen cupboard hot water storage and delivery system that could operate efficiently on a HP (ie no high temp bricks or phase change) woiod be very useful. 

I think you come up against the laws of physics here.  If you want to store energy reversibly in a domestic scenario it's either electrochemical (as in a battery), phase change (sunamp) or just heat.  The latter is simplest and you need a cheap material with a high heat capacity.  Fortunately water has that property.

 

The alternative is to deliver the energy real time, but because water has a high heat capacity that's a lot of power, more than houses need to heat them.

 

Of course you can combine the two (storage and real time heating) which is what the mini store does.

 

Sunamp with phase change is fundamentally a good idea, but reputationally it appears to have been poorly implemented and of course the material is inherently more expensive than water 

 

There are various tradeoffs which can be made, but the physics defines some bounding conditions which don't satisfy the desire of infinite hot water for minimal energy use.  That's why we need multiple solutions to fit various scenarios and a killer solution seems unlikely to emerge.

 

If showers were built with waste heat recovery everything becomes much easier, because the power required halves, which brings the requirements nearer to the physical limits with cheap materials.  But they aren't (yet) and it's a difficult retrofit.

Edited August 7 by JamesPa

[SteamyTea]

6 minutes ago, JamesPa said:

phase change is fundamentally a good idea, but

It still needs to deliver a lot of power at the phase change temperature.

As you say, it is the physics.

"for Nature cannot be fooled"

Isaac Newton

 

 

[JamesPa]

27 minutes ago, SteamyTea said:

It still needs to deliver a lot of power at the phase change temperature.

As you say, it is the physics.

"for Nature cannot be fooled"

Isaac Newton

 

 

To put some numbers on it a 300l cylinder at 45C with an input CW temp of 10C is storing 12.25kWh of usable energy.  If the requirement is to have a flow rate of 20l/min (which some apparently want) then the stored energy is being delivered at a rate of 49kW.

 

Those are both pretty big.  49kW is twice the power available from 100A single phase mains.  12.25kWh is 90 mins heating time for the average 8kW house.  If this needs to fit in the size of a combi (volume about 90l) then the energy storage density is 130Wh/l

 

Li ion batteries have a volumetric energy storage density of 0.4 to 1.6 kWh/l (latest research devices) so are capable of storing at the required density. I'm not sure what delivery rate they can sustain but I have the impression it's pretty high.  However 12kWh of li ion battery costs a lot more than your dhw cylinder and of course you can't charge them from a water boiler, whether it's a heat pump or fossil fuel.

 

In terms of thermal storage it looks like water has pretty much the highest volumetric heat capacity of any common material https://en.wikipedia.org/wiki/Volumetric_heat_capacity#:~:text=However%2C water has a very,−1⋅m−3.  Sofaik it's possible that some esoteric material exists or could exist that has a higher capacity, but esoteric materials tend to have esoteric prices.  So in terms of something cheap that can store energy by heating it has greater storage potential than water without a phase change we are probably out of luck.

 

So I think physics/materials science forces us to compromise, or use fossil fuels which have both a very high energy density and delivery rate. If we rule out fossil fuels, which we must, and also rule out phase change then it's compromise on cost or performance or both.  Intuitively phase change seems like a potential winner if you want ultimate performance in minimum volume, it's disappointing that sunamp seems to have a poor reputation and also that there are no competitors.  Otherwise it's some sort of volume/capacity trade off based on storing energy in water, hence multiple solutions.

I admit the above is a bit of a ramble, but hopefully goes some way to explaining why we currently have to compromise and very likely will have to compromise for the foreseeable future.

 

[JohnMo]

10 minutes ago, JamesPa said:

and also rule out phase change then it's compromise on cost or performance or both.

Or just a compromise on space which could be inside or if pushed outside. Then just use an UVC.

 

But the mini store is just a small thermal store with a big surface area coil. RED did very similar with a special design from Harlequin was just bigger, but had no G3 requirements.

Edited August 7 by JohnMo

[JamesPa]

35 minutes ago, JohnMo said:

Or just a compromise on space which could be inside or if pushed outside. Then just use an UVC.

My point is you have to compromise on _something_; there is not likely in the foreseeable future to be a perfect solution of the sort @Beelbeebubis asking for, because the physics/material science doesn't match our (imho unreasonable, but definitely unrealistic) expectations. 

 

A better compromise for the planet, than a vast uvc, would be an aerator, 6-8 l/min, and not expecting to have several showers in quick succession.

 

35 minutes ago, JohnMo said:

But the mini store is just a small thermal store with a big surface area coil. 

yes indeed... with a bit more capacity squeezed out by doing real time reheat.  That's probably why they couldn't patent it, too much prior art.

 

35 minutes ago, JohnMo said:

RED did very similar with a special design from Harlequin was just bigger, but had no G3 requirements

Indeed so

Edited August 7 by JamesPa

[ReedRichards]

43 minutes ago, JamesPa said:

In terms of thermal storage it looks like water has pretty much the highest volumetric heat capacity of any common material

So do we need to find another liquid we could wash/shower in that doesn't require so much energy to make it warm/hot?  I guess it would have to be filtered and re-used but that doesn't sound impossibly difficult and heat recovery could form part of that process.

[JamesPa]

3 minutes ago, ReedRichards said:

So do we need to find another liquid we could wash/shower in that doesn't require so much energy to make it warm/hot?  I guess it would have to be filtered and re-used but that doesn't sound impossibly difficult and heat recovery could form part of that process.

That's an interesting idea.  Water of course is also an excellent solvent and does no harm to humans unless the human is submerged.  An alternative liquid would need these properties too.

 

Of course we do already have one (sort of), namely aerated water, easily available by changing your shower head!

Edited August 7 by JamesPa

[JohnMo]

1 minute ago, JamesPa said:

and not expecting to have several showers in quick succession.

Does that actually really happen often, or just in peoples heads. I can remember in the 90s, we would feel our uninsulated dinky cylinder and if it wasn't hot, flick on the immersion and have a cup of tea then go for a shower.

 

Expectation has moved on in people's heads, but most people's reality is a combi boiler doing around 8 to 10L/min if they are lucky in winter. Or an invented cylinder doing not much more or less.

[SteamyTea]

6 minutes ago, JamesPa said:

dies no harm to humans

Kills thousands of people every year.

 

6 minutes ago, JamesPa said:

An alternative liquid would need these properties too.

Super critical CO₂ is marvellous at cleaning.

 

 

Dihydrogen Monoxide (DHMO) is a colorless and odorless chemical compound, also referred to by some as Dihydrogen Oxide, Hydrogen Hydroxide, Hydronium Hydroxide, or simply Hydric acid. Its basis is the highly reactive hydroxyl radical, a species shown to mutate DNA, denature proteins, disrupt cell membranes, and chemically alter critical neurotransmitters. The atomic components of DHMO are found in a number of caustic, explosive and poisonous compounds such as Sulfuric Acid, Nitroglycerine and Ethyl Alcohol.
For more detailed information, including precautions, disposal procedures and storage requirements, refer to one of the Material Safety Data Sheets (MSDS) available for DHMO:

Kemp Compliance & Safety MSDS for DHMO
Chem-Safe, Inc. MSDS for Dihydrogen Monoxide
Applied Petrochemical Research MSDS for Hydric Acid
Original DHMO.org Material Safety Data Sheet (MSDS) for Dihydrogen Monoxide (html)
Should I be concerned about Dihydrogen Monoxide?
Yes, you should be concerned about DHMO! Although the U.S. Government and the Centers for Disease Control (CDC) do not classify Dihydrogen Monoxide as a toxic or carcinogenic substance (as it does with better known chemicals such as hydrochloric acid and benzene), DHMO is a constituent of many known toxic substances, diseases and disease-causing agents, environmental hazards and can even be lethal to humans in quantities as small as a thimbleful.    
    Research conducted by award-winning U.S. scientist Nathan Zohner concluded that roughly 86 percent of the population supports a ban on dihydrogen monoxide. Although his results are preliminary, Zohner believes people need to pay closer attention to the information presented to them regarding Dihydrogen Monoxide. He adds that if more people knew the truth about DHMO then studies like the one he conducted would not be necessary.
A similar study conducted by U.S. researchers Patrick K. McCluskey and Matthew Kulick also found that nearly 90 percent of the citizens participating in their study were willing to sign a petition to support an outright ban on the use of Dihydrogen Monoxide in the United States.

Why haven't I heard about Dihydrogen Monoxide before?
Good question. Historically, the dangers of DHMO, for the most part, have been considered minor and manageable. While the more significant dangers of Dihydrogen Monoxide are currently addressed by a number of agencies including FDA, FEMA and CDC, public awareness of the real and daily dangers of Dihydrogen Monoxide is lower than some think it should be.
Critics of government often cite the fact that many politicians and others in public office do not consider Dihydrogen Monoxide to be a "politically beneficial" cause to get behind, and so the public suffers from a lack of reliable information on just what DHMO is and why they should be concerned.        Part of the blame lies with the public and society at large. Many do not take the time to understand Dihydrogen Monoxide, and what it means to their lives and the lives of their families.
Unfortunately, the dangers of DHMO have increased as world population has increased, a fact that the raw numbers and careful research both bear out. Now more than ever, it is important to be aware of just what the dangers of Dihydrogen Monoxide are and how we can all reduce the risks faced by ourselves and our families.

What are some of the dangers associated with DHMO?
Each year, Dihydrogen Monoxide is a known causative component in many thousands of deaths and is a major contributor to millions upon millions of dollars in damage to property and the environment. Some of the known perils of Dihydrogen Monoxide are:
    
Death due to accidental inhalation of DHMO, even in small quantities.
Prolonged exposure to solid DHMO causes severe tissue damage.
Excessive ingestion produces a number of unpleasant though not typically life-threatening side-effects.
DHMO is a major component of acid rain.
Gaseous DHMO can cause severe burns.
Contributes to soil erosion.
Leads to corrosion and oxidation of many metals.
Contamination of electrical systems often causes short-circuits.
Exposure decreases effectiveness of automobile brakes.
Found in biopsies of pre-cancerous tumors and lesions.
Given to vicious dogs involved in recent deadly attacks.
Often associated with killer cyclones in the U.S. Midwest and elsewhere, and in hurricanes including deadly storms in Florida, New Orleans and other areas of the southeastern U.S.
Thermal variations in DHMO are a suspected contributor to the El Nino weather effect.
What are some uses of Dihydrogen Monoxide?
Despite the known dangers of DHMO, it continues to be used daily by industry, government, and even in private homes across the U.S. and worldwide. Some of the well-known uses of Dihydrogen Monoxide are:

as an industrial solvent and coolant,
in nuclear power plants,
by the U.S. Navy in the propulsion systems of some older vessels,
by elite athletes to improve performance,
in the production of Styrofoam,
in biological and chemical weapons manufacture,
in the development of genetically engineered crops and animals,
as a spray-on fire suppressant and retardant,
in so-called "family planning" or "reproductive health" clinics,
as a major ingredient in many home-brewed bombs,
as a byproduct of hydrocarbon combustion in furnaces and air conditioning compressor operation,
in cult rituals,
by the Church of Scientology on their members and their members' families (although surprisingly, many members recently have contacted DHMO.org to vehemently deny such use),
by both the KKK and the NAACP during rallies and marches,
by members of Congress who are under investigation for financial corruption and inappropriate IM behavior,
by the clientele at a number of bath houses in New York City and San Francisco,
historically, in Hitler's death camps in Nazi Germany, and in prisons in Turkey, Serbia, Croatia, Libya, Iraq and Iran,
in World War II prison camps in Japan, and in prisons in China, for various forms of torture,
during many recent religious and ethnic wars in the Middle East,
by many terrorist organizations including al Qaeda,
in community swimming pools to maintain chemical balance,
in day care centers, purportedly for sanitary purposes,
by software engineers, including those producing DICOM software and other DICOM software tools,
by popular computer science professors,
by aspiring young adult fiction writers and mental health advocates,
by international travel bloggers,
by the semi-divine King Bhumibol of Thailand and his many devoted young working girls in Bangkok,
by the fearsome yet kind and drug-free Hells Angels motorcycle gang,
by the British Chiropractic Association and the purveyors of the bogus treatments that the BCA promotes,
by commodities giant Trafigura in their well-publicized and widely-known toxic-waste dumping activities in Ivory Coast,
in animal research laboratories, and
in pesticide production and distribution.
What you may find surprising are some of the products and places where DHMO is used, but which for one reason or another, are not normally made part of public presentations on the dangers to the lives of our family members and friends. Among these startling uses are:
as an additive to food products, including jarred baby food and baby formula, and even in many soups, carbonated beverages and supposedly "all-natural" fruit juices
in cough medicines and other liquid pharmaceuticals,
in spray-on oven cleaners,
in shampoos, shaving creams, deodorants and numerous other bathroom products,
in bathtub bubble products marketed to children,
as a preservative in grocery store fresh produce sections,
in the production of beer by all the major beer distributors,
in the coffee available at major coffee houses in the US and abroad,
in Formula One race cars, although its use is regulated by the Formula One Racing Commission, and
as a target of ongoing NASA planetary and stellar research.

One of the most surprising facts recently revealed about Dihydrogen Monoxide contamination is in its use as a food and produce "decontaminant." Studies have shown that even after careful washing, food and produce that has been contaminated by DHMO remains tainted by DHMO.
What is the link between Dihydrogen Monoxide and gun violence?
    The incidence of gun violence seems to be rising at an alarming rate. A recent stunning revelation is that in every single instance of violence involving guns, both in the U.S. and internationally, Dihydrogen Monoxide was involved. In fact, DHMO is often very available to those who would do harm to others. Meanwhile, apparently no efforts have been made to limit the availability of this potentially dangerous chemical compound.
How does Dihydrogen Monoxide toxicity affect kidney dialysis patients?
Unfortunately, DHMO overdose is not unheard of in patients undergoing dialysis treatments for kidney failure. Dihydrogen Monoxide overdose in these patients can result in congestive heart failure, pulmonary edema and hypertension. In spite of the danger of accidental overdose and the inherent toxicity of DHMO in large quantities for this group, there is a portion of the dialysis treated population that continues to use DHMO on a regular basis.
Are there groups that oppose a ban on Dihydrogen Monoxide?
In spite of overwhelming evidence, there is one group in California that opposes a ban on Dihydrogen Monoxide. The Friends of Hydrogen Hydroxide is a group that believes that the dangers of DHMO have been exaggerated. Members claim that Dihydrogen Monoxide, or the less emotionally charged and more chemically accurate term they advocate for it, "Hydrogen Hydroxide," is beneficial, environmentally safe, benign and naturally occurring. They argue that efforts to ban DHMO are misguided.
Friends of Hydrogen Hydroxide is supported by the Scorched Earth Party, a radical and loosely-organized California-based group. Sources close to the Scorched Earth Party deny any outside funding from government, industry or pro-industry PACs.

Has the press ignored this web site and the Dihydrogen Monoxide problem?
For the most part, the press has not reported on the dangers of Dihydrogen Monoxide as much as some would like. Although many private individuals have put up web sites in a major grassroots effort to spread the word, major publications have not.
Recently, attention has been paid to the subject thanks to an incident in Aliso Viejo, California.  This so-called Aliso Viejo Incident was widely reported in the media, although the director of DHMO.org, Dr. Tom Way, was called a "prankster."  Once the Associated Press started circulating the story, it became fact, and the valuable information being provided by the DHMO.org website was deemed to be "rubbish" rather than an honest and unbiased recounting of facts about a dangerous, life-endangering chemical compound.

If you are a member of the press, you may access our online Press Kit.  See the main page for access information.  This resource is for members of the press only.

 

Is it true that using DHMO improves athletic performance?
Absolutely! With the numerous allegations of amateur and professional athletes using anabolic steroids and/or blood doping to enhance performance, virtually no attention has been paid to the performance enhancing properties of Dihydrogen Monoxide. It is perhaps the sporting world's dirtiest of dirty little secrets that athletes regularly ingest large quantities of DHMO in an effort to gain a competitive edge over an opponent.

One technique commonly used by endurance athletes in sports such as distance running and cycling is to take a large amount of DHMO immediately prior to a race. This is known within racing circles to dramatically improve performance.

Sports-medicine physicians warn that ingesting too much Dihydrogen Monoxide can lead to complications and unwanted side-effects, but do acknowledge the link to improved performance. DHMO is not currently considered a banned substance, so post-race urine tests do not detect elevated or abnormal levels of DHMO.

Can using DHMO improve my marriage?
    This is a popular myth, but one which is also actually supported by a number of scientific facts. Dihydrogen Monoxide plays an instrumental role in the centers of the brain associated with feelings of emotional attachment and love. Married couples have found that regular ingestion of DHMO can improve their marriage-related activities, while couples that never ingest DHMO often find that their marriage suffers as well. 
What are the symptoms of accidental Dihydrogen Monoxide overdose?
You may not always recognize that you have been a victim of accidental DHMO overdose, so here are some signs and symptoms to look for. If you suspect Dihydrogen Monoxide overdose, or if you exhibit any of these symptoms, you should consult with your physician or medical practitioner. The data presented here is provided for informational purposes only, and should in no way be construed as medical advice of any sort.
    
Watch for these symptoms:
Excessive sweating
Excessive urination
Bloated feeling
Nausea
Vomiting
Electrolyte imbalance
Hyponatremia (serum hypotonicity)
Dangerously imbalanced levels of ECF and ICF in the blood
Degeneration of sodium homeostasis
A recently noted medical phenomenon involves small amounts of DHMO leaking or oozing from the corners of the eyes as a direct result of causes such as foreign particulate irritation, allergic reactions including anaphylactic shock, and sometimes severe chemical depression.

What is a chemical analysis of Dihydrogen Monoxide
Recently, German analytical chemist Christoph von Bueltzingsloewen at the Universitaet Regensburg identified what may be key reasons why the dangers of DHMO are ever present. According to von Bueltzingsloewen, the chemical separation of dihydrogenoxide from the hazardous oxygendihydride is extremely difficult. The two similar compounds curiously occur in nearly equimolar distribution wherever they are found. It is not clear how the two contribute directly to the dangers inherent in Dihydrogen Monoxide, although von Bueltzingsloewen believes that a synergetic mechanism, catalyzed by traces of hydrogenhydroxide, plays a major role.    
What can I do to minimize the risks?
Fortunately, there is much you can do to minimize your dangers due to Dihydrogen Monoxide exposure. First, use common sense. Whenever you are dealing with any product or food that you feel may be contaminated with DHMO, evaluate the relative danger to you and your family, and act accordingly. Keep in mind that in many instances, low-levels of Dihydrogen Monoxide contamination are not dangerous, and in fact, are virtually unavoidable. Remember, the responsibility for your safety and the safety of your family lies with you.
Second, exercise caution when there is the potential for accidental inhalation or ingestion of DHMO. If you feel uncomfortable, remove yourself from a dangerous situation. Better safe than sorry.

Third, don't panic. Although the dangers of Dihydrogen Monoxide are very real, by exercising caution and common sense, you can rest assured knowing that you are doing everything possible to keep you and your family safe.

How can I find out more about Dihydrogen Monoxide?
We would be happy to tell you more about DHMO! Send us email, and we'll gladly attempt to keep you up-to-date on current developments in the study of Dihydrogen Monoxide, its uses and misuses.
There are a number of sites on the world wide web that contain more information on DHMO and related topics. It should be noted that we do not endorse these sites, nor do we control their content or political bias.

Edited August 7 by SteamyTea

[JamesPa]

2 minutes ago, JohnMo said:

Does that actually really happen often, or just in peoples heads. I can remember in the 90s, we would feel our uninsulated dinky cylinder and if it wasn't hot, flick on the immersion and have a cup of tea then go for a shower.

 

Expectation has moved on in people's heads, but most people's reality is a combi boiler doing around 8 to 10L/min if they are lucky in winter. Or an invented cylinder doing not much more or less.

I think the answer to the first question is probably no, and your comments in the second paragraph equally true.  Yet it is what we now apparently are 'expected' to design for if retrofitting a heat pump!

 

So the real problem comes down to expectations.

[JamesPa]

8 minutes ago, SteamyTea said:

 

Super critical CO₂ is marvellous at cleaning.

I imagine capturing and reusing it to avoid a further contribution to global warming might prove tricky.

 

As for dhmo, the arguments seems a bit watered down to me.

Edited August 7 by JamesPa

[SteamyTea]

2 minutes ago, JamesPa said:

I imagine capturing and reusing it to avoid a further contribution to global warming might prove tricky.

Already done.

 

https://blancliving.co/blogs/news/how-liquid-co2-dry-cleaning-is-helping-to-save-the-planet

[JamesPa]

1 minute ago, SteamyTea said:

Already done.

 

https://blancliving.co/blogs/news/how-liquid-co2-dry-cleaning-is-helping-to-save-the-planet

From a quick scan the cleaning takes place at -5 to -10C.  Not sure that will satisfy the MCS installation rules.

[SteamyTea]

1 minute ago, JamesPa said:

cleaning takes place at -5 to -10C

Well will make for less area for blokes to clean.

[Beelbeebub]

For better or worse, the combi is the yardstick. 

 

I don't think people really need actually infinite hot water. They just want to not have to think about it. 

 

They also want the space a big cylinder takes up for other things. 

 

Right now the relatively big cylinder specified by manufacturers and installers is a bit of a barrier. Both in cost and size. 

 

The HG system is a good attempt at making the installation a bit lower friction. 

 

As long as the hot water delivery is good enough - ie the times where the customer has a tepid shower or has to wait 20mins for the cylinder to recharge are very few, then it's a great idea. 

 

A 9kw instantaneous water heater (variable power controlled to just top up the temp if too low) afterwards would extend the hot water delivery time and not fall foul of g3 regs. 

[Dave Jones]

23 hours ago, Beelbeebub said:

But it's DHW cycle is limited. 

 

For true combi performance we need to produce hot water for an infinite time. If you don't defrost you HP the capacity and efficency drop (which is why we do defrost them). That will eventually mean the amount of hot water you can instantaneously heat will fall and your bath or shower will become tepid.. You already get this if you have to many hot water draws on a combi. If someone is showering and someone else fills the bath, the flow rate and temp fall. 

 

What people really want for a "just like a combi" heat pump is an installation that takes up similar internal room to a gas boiler. 

 

As HG identified the issue is more the storage of hot water. Current approach is a large UV cylinder. This is OK if replacing a large UV cylinder but when you are swapping a vented cylinder you get the g3 issues and when you are swapping a combi you get the G3 and space issues. 

 

A combi or at most,. Kitchen unit or kitchen cupboard hot water storage and delivery system that could operate efficiently on a HP (ie no high temp bricks or phase change) woiod be very useful. 

 

the only way to get combi levels of hot water with ASHP is more tanks and a higher storage temp. From  our experience 3 x 250 L at 75C would mean zero chance of running out, below that we do run out at times, not often but it happens.

[dpmiller]

36 minutes ago, Beelbeebub said:

For better or worse, the combi is the yardstick. 

 

not everywhere. Mains gas is still quite a new thing in NI and going from a vented tank/ oil boiler/ Willis combo is a steep learning curve for many...

[JohnMo]

27 minutes ago, Dave Jones said:

our experience 3 x 250 L at 75C

Would that take up the same room as someone's flat. I suppose they would need heating, but would have nowhere to sit.