Heat Pump Hot Water Efficiency in DEAP

greenfit

Hi
Apologies if this has been done before but I cannot find the exact answer I am looking for...
I am currently researching different air to water heat pumps that will help a project meet the EPC and CPC requirements in DEAP without the need for additional renewables e.g. solar thermal or PV panels. (standard envelope spec .15 W/m2K u-values, 3m3/h/m2 airtightness, triple glazed windows, natural ventilation). However I have found that, despite the claims of virtually all of the suppliers, none of the heat pumps units I have researched achieve this. This is mainly due to how the hot water generation efficiency of these products is dealt with in DEAP i.e. a heavy penalty is applied to heat pumps that cannot heat water to appropriate temperatures and / or have an integrated immersion. (I suspect that this penalty is at best a crude method of measuring hot water generation efficiency or at worst plain wrong but as this is a compliance exercise the rules are the rules)
Does anyone know of a air to water heat pump on the market which satisfies the conditions of section G1.2 in Appendix G of the DEAP manual? i.e. can heat hot water to appropriate temperatures and does not have an integrated immersion. If you do can you PM the details? Thanks a lot

sydthebeat

i have yet to find a A2W heat pump that can, i generally include the min PV cell that gets it over the line

its worth knowing that the whole Heat Pump inputs in DEAP are under going a total review with SEAI currently.

MicktheMan

greenfit wrote: »

3m3/h/m2 airtightness, ... natural ventilation

:eek:
Seriously consider a whole house mechanical ventilation system at this air infiltration rate

MOTM

sydthebeat wrote: »

i have yet to find a A2W heat pump that can, i generally include the min PV cell that gets it over the line

its worth knowing that the whole Heat Pump inputs in DEAP are under going a total review with SEAI currently.

http://www.seai.ie/Your_Building/BER/BER_Assessors/Technical/DEAP/DEAP_public_consultation/DEAP-Public-Consultation.html

greenfit

MicktheMan wrote: »

:eek:
Seriously consider a whole house mechanical ventilation system at this air infiltration rate

Thanks Mick but I was under the impression that 3m3/h/m2 was still ok for natural ventilation..??? ...ideally of course all houses would have MVHR and a much lower AT target but can be hard to convince to commit to it

froshtyv

This is the biggest grey area that i can see in the DEAP software at the moment.

There are too many variables to just say one heat pump will comply with your Part L renewable, EPC and CPC
I have seen so many different interpretations of the EAF for hot water for heat pumps in the DEAP software.
Its hard to blame a BER assessor seeing as the SEAI left it open for interpretation.
In appendix G they say the heat pump must bring the water up to appropriate temperatures.
Define appropriate temperatures?
I know they have now said that this is to supply and store water at 60 degrees.
What information is required by the SEAI to ensure that a heat pump can actually do this?
Manufactures specification sheet? Independent test procedure?
What cylinder is used to store the water?

I have seen certain heat pump manufactures use the EN255-3 standard to use 0.75 as the EFA for hot water, but then use the SPF based on the EN14511-2, which is a standard that doesnt even test for hot water storage.
The SPF using the EN255-3 standard would have a much lower SPF when heating water to 60
So they end up using a high EFA of 0.75 and a high SPF based on the incorrect standard, so technically if the BER file was audited and this was the scenario that was found, it would be quite possible that the house would fail on compliance, which could end up with legal proceedings.

I will be very interesting to see what changes if any the SEAI make to the DEAP software when it is updated after the review process.

caesarthechimp

froshtyv wrote: »

I have seen certain heat pump manufactures use the EN255-3 standard to use 0.75 as the EFA for hot water, but then use the SPF based on the EN14511-2, which is a standard that doesnt even test for hot water storage.

My understanding of it is that if tested to EN14511-2 (or EN255-2) it is expected to heat water to 40C max. So 50% of DHW, and the other 50% from the immersion.
If tested to EN 255-3 it is expected to heat water to 50C max. So 75% of DHW. But all those listed on Harp have EN14511-2 shown in the technical data there.

Then there is the theoretical "high temperature heat pump" which would heat the water to "appropriate temperatures" and does not have a integral immersion in the system. It would heat 100% of DHW and the adjustment factor would be either 0.7 or 0.75 depending on which EN standard it was certified to. But I have yet to see a heat pump without an integral immersion fitted in the DHW cylinder. If anyone disconnects the immersion to improve the BER, they risk being sued later for causing legionella poisoning.

On the other hand there are assessors out there who will ignore these rules and just use the deap inputs that the salesman gives them. I was given a photocopy of sample deap inputs and told this is what other assessors are using; 100% DHW and 0.75 factor when in fact the system had an integral immersion and was certified to the lower standard.
However, I only got to certify the first house, and somebody else did the others. I noticed afterwards the others had only half the area of solar PV compared to the first one.

When they decide on the new procedure, more heat pumps will probably classify as the high temperature type. It will probably not be any simpler to understand though.

froshtyv

caesarthechimp wrote: »

My understanding of it is that if tested to EN14511-2 (or EN255-2) it is expected to heat water to 40C max. So 50% of DHW, and the other 50% from the immersion.
If tested to EN 255-3 it is expected to heat water to 50C max. So 75% of DHW. But all those listed on Harp have EN14511-2 shown in the technical data there.

Then there is the theoretical "high temperature heat pump" which would heat the water to "appropriate temperatures" and does not have a integral immersion in the system. It would heat 100% of DHW and the adjustment factor would be either 0.7 or 0.75 depending on which EN standard it was certified to. But I have yet to see a heat pump without an integral immersion fitted in the DHW cylinder. If anyone disconnects the immersion to improve the BER, they risk being sued later for causing legionella poisoning.

On the other hand there are assessors out there who will ignore these rules and just use the deap inputs that the salesman gives them. I was given a photocopy of sample deap inputs and told this is what other assessors are using; 100% DHW and 0.75 factor when in fact the system had an integral immersion and was certified to the lower standard.
However, I only got to certify the first house, and somebody else did the others. I noticed afterwards the others had only half the area of solar PV compared to the first one.

When they decide on the new procedure, more heat pumps will probably classify as the high temperature type. It will probably not be any simpler to understand though.

You wont find a heat pump without an integral immersion. The SEAI actually define an integral immersion as not the one found in the cylinder but the one found in the unit itself, ie a back up heater.

The new system will judge heat pumps on their combined energy labelling, like what you see when you but a new fridge.
You will have a label for heating and a for hot water.
The SEAI are to release a calculation tool in the next 2 weeks for this.
So hopefully it will be a level playing field and no more grey areas when it comes to energy adjustment factors.

MOTM

froshtyv wrote: »

The SEAI are to release a calculation tool in the next 2 weeks for this.

The website says mid to end November I think. So, 4-6 weeks.

ArraMusha

Dont see any update on this on the SEAI website today..

froshtyv

ArraMusha wrote: »

Dont see any update on this on the SEAI website today..

Its been pushed out again to the first two weeks of December.

MOTM

Methodology for heat pumps in DEAP now updated. http://www.seai.ie/Your_Building/BER/BER_FAQ/FAQ_DEAP/Energy_Requirements/How-do-I-assess-heat-pumps-in-DEAP-.html

sydthebeat

Great, another trench of pages of convoluted guidelines, methodologies and tools to add to an already over bloated system.

Is that REALLY the best they could do?

caesarthechimp

In terms of existing dwellings with pre 2016 units, the old rules still seem to apply as before.

froshtyv wrote: »

You wont find a heat pump without an integral immersion. The SEAI actually define an integral immersion as not the one found in the cylinder but the one found in the unit itself, ie a back up heater.

I think they mean an immersion in the system, ie it could be in an adjacent buffer tank/cylinder. Either way it makes no difference because the older heat pump systems can't be proven to heat the water in the taps to "appropriate temperatures" without help from the immersion, as in; "Where the heat pump has an integral immersion or the heat pump is not designed to reach appropriate temperatures for water heating, G1.1 is followed."

froshtyv

caesarthechimp wrote: »

In terms of existing dwellings with pre 2016 units, the old rules still seem to apply as before.

I think they mean an immersion in the system, ie it could be in an adjacent buffer tank/cylinder. Either way it makes no difference because the older heat pump systems can't be proven to heat the water in the taps to "appropriate temperatures" without help from the immersion, as in; "Where the heat pump has an integral immersion or the heat pump is not designed to reach appropriate temperatures for water heating, G1.1 is followed."

Believe it or not it made a huge difference as to where the immersion is located. If it was located in the heat pump unit, it didn't matter if the heat pump could reach 80 degrees flow temp on its own, as having an integral immersion automatically meant that you had to use one of the two formals in appendix g of the deal manual.

The only scenario where a heat pump could use 0.7 as an ETA in the water heating tab, is if the heat pump can store water a temperatures above 60 and not have an integral heater installed in the heat pump unit.
You would need to have certification to prove the above.

How the seai seemed to allow 0.7 to be used for certain heat pumps is beyond me.

Hopefully with the new tool this will make it a level playing field for all.

Toplink

sydthebeat wrote: »

Great, another trench of pages of convoluted guidelines, methodologies and tools to add to an already over bloated system.

Is that REALLY the best they could do?

I am only catching up with these revised guidelines now Who the hell came up with this botch of a process?


I am new to this process but I am helping out a friend of mine who is building a house. His potential A2W heat pump installer is telling me that he can achieve a COP of up to 560 based on a good envelope with a good standard of air tightness. He said he need a provisional xml file for the house before he can stand over the figures. I'll be sending it to him next week.

What sort of COP figures are ye actually seeing being used to comply with part L? 560 seems very high to me.

To get this house to comply with Part L based on the current DEAP inputs I need the A2W heat pump to achieve at least 510 COP.

Is this realistic?