Air Source Heat Pumps Do Not Work

[A_L]

12 hours ago, ProDave said:

Annual heating cost about £250

 

@ProDave, I would make that about 1750KWh of electricity. At a conservative COP of 3 that is 5250kWh of heat, presumably that includes DHW, can you estimate a split?  

[ProDave]

3 minutes ago, A_L said:

 

@ProDave, I would make that about 1750KWh of electricity. At a conservative COP of 3 that is 5250kWh of heat, presumably that includes DHW, can you estimate a split?  

No that's just heating.  DHW is about half that.  I have metering set up so it records electricity used in DHW mode separate to electricity used in heating mode.

[Thedreamer]

12 hours ago, SteamyTea said:

I is easier than working out the volume.

Timber has a specific energy of ~4.5 kWh/kg.

Another thing worth looking at is the number of rings showing on logs, that gives a good indication how long it takes to replenish that resource, quite frightening that you can burn a ten year old log in a few minutes.

But that is another topic.

 

All of the trees are home grown spruces. The oldest and tallest are around thirty years old.

 

These were planted by the father in law to provide shelter to their house, livestock and also a habitat for local wildlife.

 

All the trees cut down have been replanted with native hardwood species such as oak, birch etc 

 

12 hours ago, SteamyTea said:

Without knowing the heat losses of the building, it is hard to work out the cot of any type of heating system.

You can do a simplified calculation by working out the U-Value and areas of all the exposed components, then find some local weather data, that will give a fairly good estimate of what is needed.  Then you can look at different technologies and how they compare on capital and running costs.

 

I will look into this.

 

12 hours ago, SteamyTea said:

 

Which do you think is more complicated, your gas oven or your fridge?

Heat pumps are really very basic and have been around, unchanged, for about 50 years (the first heat pump was about 1940).

The only major change is the transition from reciprocating 'piston' compressors to rotary 'scroll' compressors.  Though is some CO₂ HPs they are going back to reciprocating pumps.

 

I don't think we can really compared a heat pump with a fridge, even if the technology is very similar. If my fridge stops working all that is needed from me is to order from Curry's etc and I plug that it. If my heat pump stops working I'm going to need somebody to come here and look and consider is a repair necessary, what component and so on.

 

I like using the stove as apart from the annual sweep, it's all within my control. 

 

My mini air source heat pump for my hot water seems to be unpopular here but it works great. 

 

12 hours ago, SteamyTea said:

The reason for this is that even the 'best' R32 refrigerant gas is still several hundred times worse that CO₂. This is legislation driven, not a technology change as such.  Heat pumps can use tap water as the refrigerant, but as water is 'the universal solvent' it does not have the longevity desired, though the performance is very good.

 

While a useful basic comparison of technologies, the running costs can vary way too much in individual households i.e. the standard deviation is very great.

When looking at the technology side, it is easy to get side tracked by the fuel costs.  These vary, and vary greatly around the world.  Japan, which has no naturally occurring coal, oil or gas, uses heat pumps.  Russia has about 150 year worth of natural gas at current consumption rates, so uses basic technology and they control temperature by opening windows.

 

Your point regarding Russia and Japan is interesting. I think this is applicable to self builders here. My set-up which is dependent on firewood works because I have the space, the tools and timber but it probably wouldn't work for others on here. It certainty would not be sustainable if we all attempted it.

 

My approach is more similar to somebody in a rural Scandinavia country, rather than somebody building in south east such as Kent.

 

12 hours ago, SteamyTea said:

The running costs do not change the efficiency of a system and can very easily be a distraction when trying to work out the best there is.

 

The efficiency of the system is of interest to me, but the savings must be factored with the initial capital contribution.

[SteamyTea]

24 minutes ago, Thedreamer said:

efficiency of the system is of interest to me, but the savings must be factored with the initial capital contribution

Yes they must. But we have to put a cost on the externalities to.

 

The servicing issue is a problem at the moment. But it is with some gas boilers, and definitely oil ones, even down here.

Generally, ASHPs are reliable and are low maintenance.

But you know that from the one you have that heats the water.

[ToughButterCup]

3 hours ago, SteamyTea said:

If only this forum had a way to easily direct people to decent static resources.

...

 

Some people might call such a resource  a book, @SteamyTea. Written slightly tongue in cheek, but I agree with you.  Static resources : not the thing of the moment are they?

 

Since I am now - at last - the proud of owner of a SunAmp UniQ, your comments about phase change piqued my interest :

4 hours ago, SteamyTea said:

...

There is a second part to the whole energy, power and temperature bit that is more relevant to heat pumps and that is phase change materials.

....

 

In the context of SunAmp equipment (Sorry to mention the trade name, I'm not sure whether there are other producers) how do the terms power, temperature and energy relate to phase change materials? And you slip another (for me white noise term) '... specific...' in there.  '... Specific energy capacity ...' What might specific energy capacity mean in SunAmp terms?

 

Do we know what the phase change material is in a SunAmp? 

[SteamyTea]

17 minutes ago, ToughButterCup said:

a book

This is the 2020's not Caxton's 14070's.

 

I think I did a bit about phase change materials on this thread:

 

[Bitpipe]

On 04/11/2020 at 13:04, SteamyTea said:

And could everyone stop getting temperature, energy and power confused, they are different thing.

 

Helping the lad prep for physics GCSE (if he ever gets to take it next year) and been covering this today

[Bitpipe]

The inverse is also true, if I've built a relatively decent spec house (not necessarily low energy or passive) then a 'builders' heating system with oversized boiler and rads may be completely unnecessary and make the house uncomfortably hot to live in.

 

If you are low energy or passive then it's critical to correctly size the system.

[SteamyTea]

26 minutes ago, Bitpipe said:

Helping the lad prep for physics GCSE

Can you copy the pages from his books. Be interesting to see how it is explained.

 

I am not sure if an oversize system would overheat a house. The control system should take care of that.

It would probably not be very efficient though.

[Bitpipe]

11 minutes ago, SteamyTea said:

Can you copy the pages from his books. Be interesting to see how it is explained.

 

I am not sure if an oversize system would overheat a house. The control system should take care of that.

It would probably not be very efficient though.

 

https://www.bbc.co.uk/bitesize/topics/z2wqtfr

 

[SteamyTea]

7 minutes ago, Bitpipe said:

 

https://www.bbc.co.uk/bitesize/topics/z2wqtfr

 

Shame they use W for work and power, even if work is intalised.

[ToughButterCup]

24 minutes ago, Bitpipe said:

... than a 'builders' heating system with oversized boiler and rads ...

 

There, right there: that's the conflict of interest I alluded to earlier in the thread. 

The builder  or in our case  plumber  who came to see our place, sucked his teeth and said;

 

"Yer wan' a 10 killerwot boiler 'n sum decent rads in thur mert " nodding in the direction of our partly completed house.

"But it's being built to a passivhaus standard" says I.

"Aye, 'as whay tha needs nu more than 10 killerwots"

 

The guy specifying the system often gets to put it in. Not in this case.

[A_L]

1 hour ago, ToughButterCup said:

Do we know what the phase change material is in a SunAmp? 

 

The bulk chemical is Sodium Acetate Trihydrate (C₂H₃NaO₂.3H₂O) but there are a few 'wrinkles'.

 

https://patents.justia.com/assignee/sunamp-limited

[joe90]

38 minutes ago, Bitpipe said:

then a 'builders' heating system with oversized boiler and rads may be completely unnecessary

yes

 

38 minutes ago, Bitpipe said:

and make the house uncomfortably hot to live in.

No, it will (should) be controlled by stats, radiator and room. 
 

it will just heat up more quickly.

Edited November 5, 2020 by joe90

[SteamyTea]

2 minutes ago, joe90 said:

it will just heat up more quickly.

It may not, if the return temperature is too high, the boiler may cut out as it assumes that the need is satisfied.

[ToughButterCup]

12 minutes ago, A_L said:

...

The bulk chemical is Sodium Acetate Trihydrate

 

I was hoping it was like  hair gel or something . So @Onoff could contemplate making his own heating system

[Onoff]

24 minutes ago, ToughButterCup said:

 

I was hoping it was like  hair gel or something . So @Onoff could contemplate making his own heating system

 

I reckon a PCM contender is the filling in McDonald's Apple Pies. By Christ does that stuff hold it's heat. Many a dark night I've bitten into one of those whilst driving to be rewarded with a scalding dollop in the lap. As you struggle to stay on the road and hold onto a steering wheel slick with mayo from the McChicken Sandwich. 

 

Should be part of the driving test imo. 

[Bitpipe]

3 minutes ago, Onoff said:

 

I reckon a PCM contender is the filling in McDonald's Apple Pies. By Christ does that stuff hold it's heat. Many a dark night I've bitten into one of those whilst driving to be rewarded with a scalding dollop in the lap. As you struggle to stay on the road and hold onto a steering wheel slick with mayo from the McChicken Sandwich. 

 

Should be part of the driving test imo. 

 

In a few years the driving test will be solely going through a McD drive through in a self driving electric car. Main test will be getting the order correct.

 

Although Uber Eats / Deliveroo / Just Eat will render that useless also.

[Oz07]

12 hours ago, SteamyTea said:

In what way, operation, design, installation, maintenance?

I have a feeling you will disagree with whatever I say!

I wouldn't know if it is a simpler option in the technical sense, just that it is the common thing to use.

Operation is hands off, though I suspect ASHP is too?

Design seems easy enough - size appropriately. Do people often size ASHP wrong?

Installation - Wouldn't know, plumber makes it look pretty easy and lots of readily available fitters.

Maintenance - The yearly check to keep the 10 year warranty seems pretty quick. What kind of warranty is on ASHP? Bet they don't need yearly inspections?

[joe90]

3 minutes ago, Oz07 said:

Bet they don't need yearly inspections?

pressurised systems do need an annual Check. My ASHP has no warranty (bought it dead cheap on Ebay ?).

[SteamyTea]

1 hour ago, Oz07 said:

I have a feeling you will disagree with whatever I say!

No, I am interested in why there is a reluctance to fit them.

 

1 hour ago, Oz07 said:

Do people often size ASHP wrong

I think so, and usually undersized,  or customers told that an ASHP cannot get the temperature high enough, so they fit gas or oil because

1 hour ago, Oz07 said:

just that it is the common thing to use

 

1 hour ago, Oz07 said:

Installation - Wouldn't know, plumber makes it look pretty easy and lots of readily available fitters

It is the same, pumps and pipes valves and distribution manifolds.  The emitters (radiators, UFH pipework) may be a different physical size, or spacing, but is hard to design a wet system differently that it already is.

 

I think there is a lot of confusion with terminology, my favourite being the names used to store hotwater, is it a cylinder a thermal store, am unvented cylinder or a vented one, buffer tanks, accumulators (though I think they are to buffer mains waiter pressure), feed and expansion tanks, pumped showers, mains pressure showers.

About time some of the plumbers put up some diagrams showing the difference.

 

But when it comes to heating the actual house (space heating), this is where a proper thermal model of the building, and local climate, is needed.  Would probably save money on all installations regardless of fuel type.

[Onoff]

13 hours ago, Bitpipe said:

 

In a few years the driving test will be solely going through a McD drive through in a self driving electric car. Main test will be getting the order correct.

 

Although Uber Eats / Deliveroo / Just Eat will render that useless also.

 

Cue Tesla having a mode whereby you can send the car on it's own to the drive through just because they can! ?

 

 

[Oz07]

How cheap @joe90?

 

I know the heating system is roughly similar, bar size of rads. But id say there's a lot more people out there that could fit a boiler but not an ashp. The plumber I use is coming up to 60 hard enough to drag him into semi modern practices as it is!

Edited November 6, 2020 by Oz07

[SteamyTea]

1 minute ago, Oz07 said:

But id say there's a lot more people out there that could fit a boiler but not an ashp. The plumber I use is coming up to 60 hard enough to drag him into semi modern practices as it is!

There is going to be no choice in a few years.

https://www.gov.uk/government/speeches/spring-statement-2019-philip-hammonds-speech

 

Still, your old plumber can service old boilers.

[Oz07]

Actually he can't - he refuses to service or fix them, just new installs.

Id imagine by 2025 he will be retired and just doing jobs for beer tokens