Preemptive Strike

[Ed Davies]

Pity the heat extracted by the slab cooling can't be used to heat the water. Instead you have to pump heat out of the slab into the outside air then at other times pump heat from the outside air into the DHW.

[ProDave]

6 minutes ago, Ed Davies said:

Pity the heat extracted by the slab cooling can't be used to heat the water. Instead you have to pump heat out of the slab into the outside air then at other times pump heat from the outside air into the DHW.

Haven't you just described an Exhaust Air Heat Pump?

 

Or how about a ground source heat pump cooling the slab and dumping it into the tank?

[NSS]

32 minutes ago, Ed Davies said:

Pity the heat extracted by the slab cooling can't be used to heat the water. Instead you have to pump heat out of the slab into the outside air then at other times pump heat from the outside air into the DHW.

True, but when it's this hot (and sunny) our PV heats our DHW without any extra input from the heat pump anyway.

[jack]

1 hour ago, Ed Davies said:

Pity the heat extracted by the slab cooling can't be used to heat the water. Instead you have to pump heat out of the slab into the outside air then at other times pump heat from the outside air into the DHW.

 

Yes, I regularly think what a shame this is.

[joth]

10 hours ago, NSS said:

Hi Janet, it is part of the Panasonic Aquarea range and, as such, connects to a Panasonic Aquarea heat pump such as ours that has (in theory at least!) the ability to provide cooling as well as heat. If you don't have the correct ASHP, I doubt you could attach the air rad.

 

This is useful to know. I think it's just a fan assisted radiator then? Several manufacturers of these about and I don't think they're particularly proprietary to the ASHP make, other than perhaps in the controller logic.

We were recommended these for upstairs but I thought the fan a bit intelligent and gone for an air ducted solution instead. I hadn't thought about cooling mode with them, which could be very effective delivery into the room with the fan assistance.

(And yes, I'm writing this laying in bed after failing to sleep for the last 3 hours due to the heat. And thunder)

 

 

[jack]

3 hours ago, joth said:

This is useful to know. I think it's just a fan assisted radiator then?

 

I think that's right. From memory, they seemed hugely expensive for what they are.

[Ed Davies]

12 hours ago, ProDave said:

Haven't you just described an Exhaust Air Heat Pump?

 

Not really, as an exhaust air heat pump exhausts the cooled air, sucking more warm air in from outside. If it had the option to blow the air in the opposite direction or re-circulate it then maybe.

 

11 hours ago, NSS said:

True, but when it's this hot (and sunny) our PV heats our DHW without any extra input from the heat pump anyway.

 

Yes, optimizing operation on sunny days doesn't make a lot of sense. Particularly in the UK.

[joe90]

Quite hot here yesterday, my son and I stood by the ASHP whilst it was heating the DHW getting a blast of nice cold air!!!, he remarked “was it possible to duct that cold air back into the house “?. I may look into cooling the slab (after I get the last 90% of work done) but do wonder how often, for our location, it would be needed. These are the temps we go on holiday abroad for!!,!

[Ferdinand]

With non of the ASHP gubbins I managed to get out inside temp in the kitchen down to 23.5C this morning - not comfortable for me. It was at 25C last night.

 

Suspect that the step I really need to take is a veranda on the S side across my office and the front lounge (soon to be bedroom), and move some solar panels. That will be a 2020 project, maybe.

 

F

[joth]

2 hours ago, joe90 said:

Quite hot here yesterday, my son and I stood by the ASHP whilst it was heating the DHW getting a blast of nice cold air!!!, he remarked “was it possible to duct that cold air back into the house “?. I may look into cooling the slab (after I get the last 90% of work done) but do wonder how often, for our location, it would be needed. These are the temps we go on holiday abroad for!!,!

Your son and I were in well tune this morning then!

I was thinking about the Ed's comment (re. pity not to capture the ejected heat energy to warm DHW_ and realized in summer this is marginal gain as the building needs to be a "net exporter" of heat energy to outside regardless, to battle against overheating. So rather than focus on capturing the wasted heat export (which low grade energy anyway) and bring back into the hot water tank, wouldn't it be more efficient overall to focus on capturing the wasted cold-air export when running the ASHP to heat DHW. Cue son-of-Joe.

 

My proposed solution [see quick sketch attached] that requires no new moving parts,  is simply to relocate the ASHP from ground-level up onto the flat roof at the rear of the house. We have 2 rooflights planned there, if I make one of them open "backwards" with the aperture pointed towards the ASHP, then it's a simply a case of cranking that open when the ASHP is in heat mode and the indoors is overtemperature. A 1.5m x 1m long rooflight with 25 degree opening will give 1m x 0.7m opening, enough to capture a good portion of the draft, and being cold it'll naturally drop down into the opening anyway.

 

Downsides are numerous:  the noise and possible mess of having it on the flat roof there, right overhead the dining area, and outside a bedroom window.  Probably also needs the flat roof re-specified to be safely walkable, for servicing. But on the flip side, it would make the pipe runs to the services room way shorter and simpler (no need to go under the slab).

 

Realistically, unlikely I'll consider it further, but always  fun to think about further optimizations!

 

 

Edited July 24, 2019 by joth

[Jeremy Harris]

Regarding noise, I've been very pleasantly surprised at how quiet the outdoor unit is.  All that can be heard is a very faint whirr from the fan, and that can only be heard when standing pretty close to it.  The compressor seems to be silent.  I was a bit concerned about compressor noise being transmitted into the structure, as the unit is mounted on a wall bracket, but there doesn't seem to be any noise transmitted at all as far as either of us can tell.

 

The indoor unit makes more noise than the outdoor unit when running at full blast, but is nearly silent when running at it's lowest setting.

[joth]

4 minutes ago, JSHarris said:

Regarding noise, I've been very pleasantly surprised at how quiet the outdoor unit is.  All that can be heard is a very faint whirr from the fan, and that can only be heard when standing pretty close to it.  The compressor seems to be silent.  I was a bit concerned about compressor noise being transmitted into the structure, as the unit is mounted on a wall bracket, but there doesn't seem to be any noise transmitted at all as far as either of us can tell.

 

The indoor unit makes more noise than the outdoor unit when running at full blast, but is nearly silent when running at it's lowest setting.

Yes, I'm becoming more comfortable with the noise risk -- previously I'd not have even entertained this location for it (higher up, and nearer our closest neighbour) 

  I think the air transmitted noise with my idea  could be quite manageable -- especially if we keep the unit well maintained (see other point about being harder to service up there). The real concern is ground transmitted noise/vibration coming through the flat roof, or wall if we bracketed it back there.  This is the aspect that got the sharpest disapproval when I briefly floated the idea with the management. (and also: risk of it being rather unsightly, looming over the roof window)

 

 

[ProDave]

On 23/07/2019 at 10:18, ProDave said:

Okay I hit a problem trying cooling on ours.

 

I tried to set cooling mode on the LG controller, but it would not allow me to select that option. So I dug out the manual.

 

I find that "cooling" mode is not available when you have opted to use an external room thermostat input.  I use the room thermostat input as that is what allows me to control the heating from a normal programmer using the "call for heat" contact from the UFH manifold as the "thermostat" contact to the ASHP.

 

To disable the room thermostat option (and thus allow cooling mode) would require opening up the ASHP and changing a DIP switch on the controller board. It is not even a software parameter that you can change.

 

Okay, I have solved this.  It took a phone call to LG tech support as the manual is far from being clear. Interesting before he would answer any questions re cooling, he first asked am I claiming the RHI.

 

When "room thermostat" is enabled by the DIP switch on these LG Therma V units, the electrical connections have 2 thermostat inputs, one for heating and one for cooling.  So I have tried it this morning. I have just connected a manual switch to the cooling thermostat input and lo and behold the ASHP fires up in cooling mode.

 

In order to get the water to flow around the UFH and open all the right valves, I have had to turn the "heating" on and turn up the room thermostats.  This of course now means that both the heating and cooling thermostat inputs to the ASHP are active.  I am happy to report that cooling seems to take priority in this situation and I now have water at 18 degrees flowing through my UFH pipes.  I will leave it running for a while and keep a check for condensation etc and see how cool the actual floor temperature gets.

 

Now I know cooling mode works and is after all easy to initiate, my longer term plan is to get 2 small fan coil units, one for each of the main bedrooms.  It will be easy to tee into the flow and return in the plant room above the garage via another motorised valve and then run the pipes through the ceiling above the main bedroom.  

 

If anyone comes across 2 small cheap Fan Coil units please let me know.

[joth]

2 hours ago, ProDave said:

 I now have water at 18 degrees flowing through my UFH pipes.  

 

Wonderful news! I had two builders and my architects in our (pre-renovation) house today... very funny how the conversation came back to "what a good idea ASHP cooling is"

 

 

2 hours ago, ProDave said:

Interesting before he would answer any questions re cooling, he first asked am I claiming the RHI.

 

 

Did he explain why he needed to know? I'm curious how much push back they do on this, given cooling is specifically permitted under RHI (but must  not be included in subsidy calcs). 

 

 

[ProDave]

I ran it for about 3 hours, and turned the water temperature down to 16 degrees.  There was no sign of condensation on the manifold or any of the pipes entering or leaving the manifold so I assume that means it was okay and there won't be any condensation within the actual floor.

 

In that time the floor surface temperature dropped about 1 degree.

 

I have turned it off now, it is not as warm today and outside is now cooler than inside so I have gone back to "open window" cooling

[Stones]

2 hours ago, joth said:

 

Did he explain why he needed to know? I'm curious how much push back they do on this, given cooling is specifically permitted under RHI (but must  not be included in subsidy calcs). 

 

 

I just had a read of the RHI eligibility and conditions and could not find anything about cooling  not being permitted.  By definition, as it does not form part of the calculations you would not be paid for it (so no 'cash for ash') but as far as I can see, it isn't prohibited.  Of course depending on the metering set up (for those installed 2018 onwards) then excessive use / renewable heat generated may be flagged up and investigated.  Wouldn't seem to be an issue for those whose payments are based on 'deemed' calculations.  Anyone reading this, please satisify yourself that this is the correct position.

 

Another warm day here and I've switched on the cooling.  Easy to activate the function via a dip switch setting.  Control is limited on my system to on / off and specifying the cooling flow temperature, albeit operation can be timed. Seems to be working, in the sense return temperature from the slab slowly dropping. Pipework cool, with a film of condensation on the UFH manifold, so keeping an eye on things -  RH higher than normal today.  Strange to feel warm air expelling from the outdoor unit rather than the usual cold!

[newhome]

24 minutes ago, Stones said:

I just had a read of the RHI eligibility and conditions and could not find anything about cooling  not being permitted.

 

It definitely used to state that it wasn't allowed. Let me see if I can find it (or they may have altered it). I can see why they might be pedantic as the incentive is supposed to be for producing heat. Hell, you are not even allowed to use ST for space heating for some reason best known to them .... 

 

 

[scottishjohn]

7 hours ago, joth said:

Your son and I were in well tune this morning then!

I was thinking about the Ed's comment (re. pity not to capture the ejected heat energy to warm DHW_ and realized in summer this is marginal gain as the building needs to be a "net exporter" of heat energy to outside regardless, to battle against overheating. So rather than focus on capturing the wasted heat export (which low grade energy anyway) and bring back into the hot water tank, wouldn't it be more efficient overall to focus on capturing the wasted cold-air export when running the ASHP to heat DHW. Cue son-of-Joe.

 

My proposed solution [see quick sketch attached] that requires no new moving parts,  is simply to relocate the ASHP from ground-level up onto the flat roof at the rear of the house. We have 2 rooflights planned there, if I make one of them open "backwards" with the aperture pointed towards the ASHP, then it's a simply a case of cranking that open when the ASHP is in heat mode and the indoors is overtemperature. A 1.5m x 1m long rooflight with 25 degree opening will give 1m x 0.7m opening, enough to capture a good portion of the draft, and being cold it'll naturally drop down into the opening anyway.

 

Downsides are numerous:  the noise and possible mess of having it on the flat roof there, right overhead the dining area, and outside a bedroom window.  Probably also needs the flat roof re-specified to be safely walkable, for servicing. But on the flip side, it would make the pipe runs to the services room way shorter and simpler (no need to go under the slab).

 

Realistically, unlikely I'll consider it further, but always  fun to think about further optimizations!

 

 

my ASHP is mounted on a garage roof and it is on the special sound absorbing mounting which looks like a big slab of concrete ,but is actually hard foam  and noise is transmitted to inside of building --not a lot but as much as the sound when viewed from outside the building 

If you are putting it on a roof which is made from beams and osb etc --you will get noise transmitted through it 

If roof is concrete I,m sure it will be silent

[newhome]

There are a number of references to cooling needing to be disabled on this forum ...

https://forum.buildhub.org.uk/topic/2776-overheating/?do=findComment&comment=42663

 

 

https://forum.buildhub.org.uk/topic/3559-rhi-up-by-a-third-if-you-installed-after-14-dec-2016/?do=findComment&comment=59426

 

https://forum.buildhub.org.uk/topic/3559-rhi-up-by-a-third-if-you-installed-after-14-dec-2016/?do=findComment&comment=59440

 

Maybe because cooling is not eligible for the RHI payment. How could you tell what was heating only if it did both? 

 

 

[Stones]

50 minutes ago, newhome said:

 

It definitely used to state that it wasn't allowed. Let me see if I can find it (or they may have altered it). I can see why they might be pedantic as the incentive is supposed to be for producing heat. Hell, you are not even allowed to use ST for space heating for some reason best known to them .... 

 

 

13 minutes ago, newhome said:

There are a number of references to cooling needing to be disabled on this forum ...

https://forum.buildhub.org.uk/topic/2776-overheating/?do=findComment&comment=42663

 

 

https://forum.buildhub.org.uk/topic/3559-rhi-up-by-a-third-if-you-installed-after-14-dec-2016/?do=findComment&comment=59426

 

https://forum.buildhub.org.uk/topic/3559-rhi-up-by-a-third-if-you-installed-after-14-dec-2016/?do=findComment&comment=59440

 

Maybe because cooling is not eligible for the RHI payment. How could you tell what was heating only if it did both? 

 

 

 

I can't find anything that specifically excludes or prevents the use of a heat pump for cooling, but would certainly agree in not being specifically identified as eligible, you could not get any RHI payment for cooling:

 

https://www.ofgem.gov.uk/system/files/docs/2018/07/essentialguideforapplicants_july_2018.pdf

 

'The table on the next page shows a summary of the eligibility requirements, eligible purposes and ineligible purposes of heat generation for the different renewable technology types. The eligible and ineligible purpose will usually correspond to a design feature of the renewable technology. Your renewable heating system must not be designed or installed to allow uses that are not considered eligible for the purpose of the Domestic RHI scheme. Note that your heat pump or biomass system may also generate heat that is ‘non eligible’, however you’ll only receive payment for eligible heat produced. Criteria for each type are explained in more detail in the figure on the next page.'

 

If you were to take mine, it was installed as it came from the manufacturer, i.e. cooling function disabled,  but there is nothing to stop me activating the cooling mode by flipping the dip switch, and my unit is on the list of accredited equipment.

[joth]

1 hour ago, Stones said:

but would certainly agree in not being specifically identified as eligible, you could not get any RHI payment for cooling:

 

https://www.ofgem.gov.uk/system/files/docs/2018/07/essentialguideforapplicants_july_2018.pdf

 

page 13 of that pdf makes it clear the heat pump is not ineligible just because it supports cooling:

 

Air source heat pump [...]  "They may also provide cooling."

 

Page 11 also states the HP may provide water cooling 

 

Yeah the key thing is the energy used for cooling is not included in the claim for payment.

 

 

 

Edited July 24, 2019 by joth

[newhome]

1 hour ago, Stones said:

If you were to take mine, it was installed as it came from the manufacturer, i.e. cooling function disabled,  but there is nothing to stop me activating the cooling mode by flipping the dip switch, and my unit is on the list of accredited equipment.

 

You've probably signed somewhere to say that you agree not to alter anything and that they can come and inspect it but I very much doubt that they would bother, plus if you knew they were coming you could just switch it back! 

[jack]

11 hours ago, joth said:

 

page 13 of that pdf makes it clear the heat pump is not ineligible just because it supports cooling:

 

Air source heat pump [...]  "They may also provide cooling."

 

Page 11 also states the HP may provide water cooling 

 

Yeah the key thing is the energy used for cooling is not included in the claim for payment.

 

Exactly this.

 

Also, if you aren't being metered (and most aren't), you're paid on nominal usage anyway. You're paid the same no matter what your actual usage.

[dpmiller]

a couple of Qs re cooling

Aren't the Salus autobalancing actuators bidirectional? How do they respond to cold flow?

What about the manifold's TMV, does it get manually opened or is there a bypass added?

[Jeremy Harris]

11 minutes ago, dpmiller said:

a couple of Qs re cooling

Aren't the Salus autobalancing actuators bidirectional? How do they respond to cold flow?

What about the manifold's TMV, does it get manually opened or is there a bypass added?

 

 

The Salus actuators don't care about the direction, they just try to establish a temperature differential between the two (unmarked) sensors.  The temperature differential they aim for depends on the flow temperature, so if this is less than 30°C the valve will aim to get a 4°C differential, if the flow temperature is over 30°C then the actuator will try to maintain a 7°C differential.  So, when in cooling mode the actuator tries to maintain a 4°C temperature differential between flow and return, which seems to be OK (it's the same differential as it tries to maintain in heating mode for us).

 

The manifold TMV just fully opens, as it tries to get the manifold temperature up to the set value and can't, so it stays wide open.  The manifold temperature in cooling mode is then determined by the ASHP set temperature.