ASHP, how to decide - I just don't get it!

[Jimbo37]

A pointer, please. I'm building new and I have opted for ASHP (I've seen nothing especially wonderful about ASHP, but it seems to deliver at a comparible cost to oil, and easier to get BC/SAP on board, but this is not the point). I'm in N Ireland and have 3 prices from installers that use their suppliers design service (Grant, Warmflow and another). None of the 3 can provide any detailed information on what their proposed system is, basically " in case the design is copied". I want to know a lot before i decide, from pipe size to zones, to controls and equipment, coz i get one shot at this, its expensive, and must work without me having to get a degree in Turning-On-The-Heat!!. 

 

Until this moment, I assumed the supplier was the cautious one, but as I write I realise that does not stack up because having designs with their equipment out there is good.

 

Anyhow, has anyone else had this issue? Do I just hold a tight reign, or is there a better way to choose?

Edited May 25, 2023 by Jimbo37

[Conor]

There are so few people in NI doing this, it's frustrating. I got in touch with Daly and Grant, don't think either got back to me.

 

That's the reason why I went the DIY route. Designed the UFH in loopcad. There are many suppliers online that will do this for you as well, e.g. Wunda. It doesn't have to be done by the ashp supplier ) installer as it's kinda separate anyway, the ashp is just a heat source and the UFH is controlled separately normally.

 

I also found it hard to actually get a heatpump. Ended up with a coolenergy. I used my plumbers and spark to connect up and commission the system. It's really easy as the only work needed was connecting the flow and returns the the buffer / cylinder, power supply and a data cable. Then turn the thing on. 

 

I took me a good year + of reading here, other places and just a lot of thinking time to come up with what we have now... And it works... And I'm happy and it's worked flawlessly and came in at under £9k finished.

[JohnMo]

2 approaches really to install and control. Lots of zones and buffer, or 1 zone then no need for buffer.  In all cases you really need to run on weather compensation to get the best efficiency. The approach taken depends a lot on how you live in the 24/7, or out at work for 12 hrs.  If the later radiators may be better than UFH due to response time.

 

Basically you need low flow temps to heating and for DHW a cylinder with a big heating coil (3m2).

 

UFH design is another topic really.

 

Download the Grant manual, that will tell you exactly how it will be installed.  Pipe sizes depend on circulation rate required, for the ASHP, pipe lengths and bends and the resulting pressure drop. It's sized to suit each install (or should be).

[SteamyTea]

  On 26/05/2023 at 06:43, JohnMo said:

Lots of zones and buffer, or 1 zone then no need for buffer.

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Possibly no need for a buffer may be more accurate.

I am still of the mind that a buffer/volumizer is always worth fitting.  They do have to be designed in from the start, not added as an afterthought.

[ProDave]

The "ASHP Industry" is really doing it's best to sully the reputation of ASHP's and drag it down to the level of cheap double zlazing.

 

For a new build that we assume is well insulated an ASHP makes a lot of sense.  It is just a shame you get silly things like this where they won't tell you anything or the other thing you get is the silly over inflated prices of MCS installers.

 

As it is a new build do you have the insulation levels and expected air tightness, then you can easily do the heat loss calculations yourself using the spreadsheet available on this forum and design your own system.  And if you want to avoid all the cloak and dagger nonsense you have , just buy the kit and employ a plumber and an electrician to install it.  The Grant one is probably the easiest for a DIY install.

 

 

[Jimbo37]

  On 26/05/2023 at 05:47, Conor said:

There are so few people in NI doing this, it's frustrating. I got in touch with Daly and Grant, don't think either got back to me.

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Exactly,and I'm nervous that if I insist on info, they'll walk away.

 

  On 26/05/2023 at 06:43, JohnMo said:

2 approaches really to install and control. Lots of zones and buffer, or 1 zone then no need for buffer.  

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Is one approach better than the other? I think @SteamyTea prefers the buffer approach.

As I have a main contractor and a job, I'm aiming to be informed of the detail, and influence it if I have concerns, rather than DIY. As a sanity check - this is reasonable and sensible, right?

 

 

 

[ProDave]

  On 26/05/2023 at 07:38, Jimbo37 said:

Exactly,and I'm nervous that if I insist on info, they'll walk away.

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If they do that, you have dodged a bullet, they would not have been a company I would want to do business with.

[Jimbo37]

  On 26/05/2023 at 07:12, ProDave said:

It is just a shame you get silly things like this where they won't tell you anything or the other thing you get is the silly over inflated prices of MCS installers.

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Who do you think is behind the withholding, the supplier or installer?

[JohnMo]

  On 26/05/2023 at 07:45, ProDave said:

If they do that, you have dodged a bullet, they would not have been a company I would want to do business with.

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Couldn't agree more.

 

ASHP, have a defined min flow rate, if they don't see it they shutdown on an error code. The only reason you need a buffer is if you do not meet the min flow limit, by having small zones that can be run independently of the others. If you can meet the min flow rate by having zones big enough the buffer just adds inefficiency.

 

Withholding info because they have just priced (with plenty of fat) not done detail design, and will not until they get the job.

[Jimbo37]

  On 26/05/2023 at 08:04, JohnMo said:

Withholding info because they have just priced (with plenty of fat) not done detail design, and will not until they get the job.

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Ah, that is smoke and mirrors, and somewhat high handed.

 

As always, thanks all for your comments

 

[SteamyTea]

  On 26/05/2023 at 08:04, JohnMo said:

If you can meet the min flow rate by having zones big enough the buffer just adds inefficiency.

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Almost.

You may get short cycling when close to the minimum flow rate, especially if you are running at the lower end of the temperature window.

If the buffet/volumizer, and associated pipework is properly insulated, then there not many thermal losses. 

  On 26/05/2023 at 08:10, Jimbo37 said:

Ah, that is smoke and mirrors, and somewhat high handed

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Mostly, but as you have found out, it is hard to get decent information, this leads to customer ignorance. Ignorance in the proper meaning.

Trying to explain, via a sales or remote technical person all the nuances, when the basics are not understood, leads to customer confusion. Let's face it, many people still struggle to understand Economy 7, let alone the multitude of ToU tariffs available today.

Terms like 'refrigerator in reverse', 'low grade heat', 'only work in a well insulated house' (how often do we hear that unqualified statement on here), 'they don't work when it is cold', energy and power constantly mixed up, and no explanation about what they are  and what uses of the term means, and even the experts on the radio getting latent heat and sensible heat mixed up, just adds to the general ignorance.

 

A first year science students does not learn any new science, what they are taught is 'unlearning'. All those simplistic, basic ideas and examples have to be broken down and rebuilt. It is why, after 120 years, the public really don't understand Quantum Physics, they had 400 years to badly understand Newtonian Physics, then get told it is wrong.

No wonder there is distrust in science. We can create an effective vaccine in record breaking time, while still believing that Bill Gates is implanting microchips into all humans, and 5G masts caused COVID. Lots of education is not helping.

There is a thread on here from someone that had never heard of a heating system that stays on 24/7, said it was ridiculous.

I wanted to point out that most heating systems are in 24/7, just that during that window they may not be consuming any energy, and may, or may not, be releasing energy. Economy 7 is a classic example. It is on all day and night, the difference is that it only received energy for a limited period of time, it is always releasing energy. If it goes 'cold', that just means it is either incorrectly sized, or being used badly, nothing to do with the underlying technology.

Explaining to a customer what the problem is, during an hours sales visit just ends in useless soundbites.

Edited May 26, 2023 by SteamyTea

[JohnMo]

  On 26/05/2023 at 08:44, SteamyTea said:

the buffet/volumizer, and associated pipework is properly insulated, then there not many thermal losses

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But if installed with a normal, instead of a large well designed buffer, you get mixing of the flow and return water, leading to heat pump having to run a few degrees hotter. Leading to a lower CoP. If installed as volumiser in the return leg that's ok but doesn't seem to happen that much.

 

  On 26/05/2023 at 08:44, SteamyTea said:

You may get short cycling when close to the minimum flow rate, especially if you are running at the lower end of the temperature window

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If you have a single or a couple of large zones designed to exceed the min flow rate, you shouldn't have an issue. Also don't install modulating radiator valves, as these slowly strangle the flow. Just balance the flows, which seems to beyond of most ASHP installers for some reason.

[SteamyTea]

  On 26/05/2023 at 10:54, JohnMo said:

But if installed with a normal, instead of a large well designed buffer, you get mixing of the flow and return water, leading to heat pump having to run a few degrees hotter

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The smaller the temperature difference, the longer you need to run it. So within reasonable operating conditions, probably no difference. 

 

I think, as tried to explain in my previous post, the whole thing is a lit more nuanced than people think.

The same us true for a gas boiler setup, not many of them are close to efficient, but when NG was tuppence a kWh, no one gave a (expletive deleted), which just shows how little the is understood.

  On 26/05/2023 at 10:54, JohnMo said:

Just balance the flows, which seems to beyond of most ASHP installers for some reason.

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Yes, really needs a machine to do it, better than a plumber's mate.

Edited May 26, 2023 by SteamyTea

[JamesPa]

  On 26/05/2023 at 07:12, ProDave said:

The "ASHP Industry" is really doing it's best to sully the reputation of ASHP's and drag it down to the level of cheap double zlazing.

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My personal theory is increasingly that it's not the ashp industry that is doing this, it's the grant harvesting industry.  It seems to me that many of the people in the business can't possibly care about the long term, which they must know doesn't matter to them because they are there only to harvest grants and go bust when or before they run out.  Of course there are some gooduns, but they seem to be in the minority.  So much for the grant stimulating the training of the industry.

 

The question is, how to recover?  I've thrown out a few radical ideas on the ASHP forum to try to stimulate discussion but they are, to a significant extent, shouted down.  

[Post and beam]

  On 26/05/2023 at 08:44, SteamyTea said:

We can create an effective vaccine in record breaking time, while still believing that Bill Gates is implanting microchips into all humans, and 5G masts caused COVID. Lots of education is not helping.

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To be fair, unlikely to be the same people at the far ends of this scale

[SteamyTea]

  On 26/05/2023 at 14:53, Post and beam said:

To be fair, unlikely to be the same people at the far ends of this scale

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Exactly, one group is ignorant of science, the other isn't.  It is how to educate the vast majority.

The science and theory behind heat pumps is talk at secondary school but not reinforced often and then forgotten.

Madcap ideas that skip the science and theory are reinforced ever day, even within the heating industry.

[TonyT]

 

https://heatpumps.co.uk

 

The author has been doing this for 30plus years, some good info, you tube videos etc

worth a look

[JamesPa]

  On 26/05/2023 at 14:58, SteamyTea said:

The science and theory behind heat pumps is talk at secondary school but not reinforced often and then forgotten.

Madcap ideas that skip the science and theory are reinforced ever day, even within the heating industry.

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I'm not sure how much science designers/installers really need to know.  Some obviously, but nothing much beyond the difficulty of O level physics and maths.  They do need a good problem solving brain,  a good toolkit of options, some common sense, and some sound techniques. It seems that they aren't currently given this by MCS.

 

On another thread I dispute the idea that system sizing, which is the fundamental building block for the system design, should, in a typical retrofit, be based on purely theoretical calculations.  There is ample evidence that the fabric assumptions simply aren't good enough on their own.  But it's drummed into them by MCS that the spreadsheet does the job. 

 

In a sense it _does_ do the job, in that nobody is likely ever to succeed in suing an installer or getting MCS to take action if the designer has followed the rules, even though it may result in a poor and overpriced system.  From an installers point of view, and even more so from the pov of a grant harvester, that's all that matters.

 

The hydrogen ready/fossil fuel sharks must be rubbing their hands with glee.

[SteamyTea]

  On 26/05/2023 at 15:48, JamesPa said:

The hydrogen ready/fossil fuel sharks must be rubbing their hands with glee.

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They are frequently rubbishing heat pumps.

[Jimbo37]

On grants, being the cynical sort, I'm assuming that nobody (other than the homeowner) really gives a monkeys whether the technology actually works, reduce costs or reduces footprints. I expect the main concern is that when 2030 comes, we can multiply the number of installs by some other number to declare some big victory and reduce any fines due for breaching our carbon-reduction commitments. Maybe I sound too cynical, but in my last home (in R of Ireland) I had to fight tooth n nail not to lose my grant because I refused to let the retrofit cwi bead installer drill a drafty 4 inch ventillation hole in all rooms. 

 

Referring back to my op, and the discussion above, I'll hold tight again and won't buy blind. Thanks all for help.

[SteamyTea]

  On 26/05/2023 at 22:51, Jimbo37 said:

I'll hold tight again and won't buy blind

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  On 26/05/2023 at 15:48, JamesPa said:

'm not sure how much science designers/installers really need to know.

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I think you/they only need to know about heat capacity of materials, energy density, combined gas law and the difference between energy and power.  Newtons Law of Cooling would be an added bonus (but then it is a bonus for the world).

The rest is pipe fitting.

Probably the biggest problem is controllers, too many on the market and no standard interface.

[SteamyTea]

  On 26/05/2023 at 15:31, TonyT said:

 

https://heatpumps.co.uk

 

The author has been doing this for 30plus years, some good info, you tube videos etc

worth a look

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Not read it.

 

Heat_Pumps_for_the_Home_-_John_Cantor.pdfFetching info...

[JamesPa]

  On 26/05/2023 at 22:51, Jimbo37 said:

Referring back to my op, and the discussion above, I'll hold tight again and won't buy blind. Thanks all for help.

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As your journey continues please feel free to post again here, or perhaps better still (because its probably more actively monitored) in the Heat Pump topic under the Renewable Energy section of this forum.  There is an enormous amount of expertise and knowledge here and, whilst people may disagree, at least ideas can be tested.

[SteamyTea]

  On 27/05/2023 at 08:11, JamesPa said:

There is an enormous amount of expertise and knowledge here and, whilst people may disagree, at least ideas can be tested.

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All good science is tested on dumb animals.

Should be a Government Slogan, just got to condense it to 3 words.  @Adsibob is the slogan man.

[TonyT]

  On 27/05/2023 at 08:08, SteamyTea said:

Not read it.

 

Heat_Pumps_for_the_Home_-_John_Cantor.pdf 15.75 MB · 2 downloads

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I know I bought the book last year, and contributed to the author for his efforts