ASHP Costing £40 a day and cold upstairs

[TonyT]

4 hours ago, GrantMcscott said:

yes it has been cold -15oC but last night is was about 2oC but windy so I suspect I have air leaks and when the master bedroom door is closed and you put your hanf below it you can feel a draught as we do nto have carpets yet.

 

We have not had an air tightness test yet as not ready for it

 

 

Edited December 17, 2022 by TonyT

[Onoff]

Does this thread not prove the massive attention to detail needed in building a Passiv ezque house? OK'ish airtightness just isn't good enough.

 

Mass house builders doing it, like is being advocated in Scotland, never going to work.

 

Blessed is he who asks for that 200mm of tape to finish off around his window. 

[Bozza]

3 minutes ago, Onoff said:

Does this thread not prove the massive attention to detail needed in building a Passiv ezque house? OK'ish airtightness just isn't good enough.

 

Mass house builders doing it, like is being advocated in Scotland, never going to work.

 

Blessed is he who asks for that 200mm of tape to finish off around his window. 

You are 100% spot on @Onoff. Plonking an ASHP on the back of a tiny standard UK mass new build is just not going to work.  Some of these mass developer houses are sooo small where are they going to put big rads anyway.  They will take up an entire wall in every room.    

My self build had to get a airtightness test before sign off so I presume that will be required by major builders.  Mine failed because is was too airtight & we had to install trickle ventilation which was a nice problem to have TBH.

 

 

[Onoff]

10 hours ago, Bozza said:

Mine failed because is was too airtight & we had to install trickle ventilation which was a nice problem to have TBH.

 

 

Does an MVHR compensate for a too airtight build?

[GrantMcscott]

10 hours ago, Onoff said:

Does this thread not prove the massive attention to detail needed in building a Passiv ezque house? OK'ish airtightness just isn't good enough.

 

Mass house builders doing it, like is being advocated in Scotland, never going to work.

 

Blessed is he who asks for that 200mm of tape to finish off around his window. 

I am not looking for a Passiv house just a house that is comfrable and not extremly cold to live in.  I currently can not use the master bedroom as it is to cold but it is a big room with lots of glass.

 

I know there is an issue with the air barrier as the cowboy builder did not fit it in the joist zone but at the time it was pointed out there was nothing I could do about it.  So there is a barrier down stairs and one upstairs and it was all fitted after the upstsirs floor and internal walls were put in.  So the top an bottom of it is not sealed as there is nothing to seal it to.

 

The heating is Warmflow AS03-R32 downstairs there is UFH with 7 zones and 1 zone upstairs the controls are Emmeti TR3100.  Down stairs are all set to 20 oC from 06.30 to 20.30 and then they go down to 18oC.  

 

Wood burning stove is on all day from about 07.00 to 22.30 and all doors are open down stairs and this stops UFH coming on in other rooms as the are warm enough with weasther above 0oC.

 

Master bedroon is to cold to use need to work out why and upstairs it feels drafty.

 

 

[Onoff]

I feel for my new neighbours. Same basic house construction as mine, circa 1930. They've just re-roofed and ewi is yet to be done. In fact their planning application waxed on about the refurb resulting in a "thermal envelope".

 

The external finish and attention to detail looks brilliant and they've had new windows. Not sure if they're 3G but they still appear to be in the outer leaf (it could tbh be solid brick with no cavity). The place was suspended timber floors, I don't know what they've done there. The work was done by their extended family who are builders. 

 

The thing is they have an ASHP fitted before things shot up. I'm wondering how they're fairing now.

 

Hoping for a tour sometime. I watched their application proceed and on the basis of it am seeing the same local architect tomorrow hopefully. 

 

 

[Miek]

13 hours ago, JohnMo said:

If you install the system around a flow temp of 30 at -7, so a well insulated UFH, there is no reason it should cost more to heat your house.  A Media 6kW monobloc at -7 and 30 degree flow temp will give a CoP of 3.4.

 

 

That's fine in theory, but what about the defrost cycle. Once the evaporator starts to ice up, which they do quite frequently once they are below the dew point and below freezing then the COP figures go out the window IMO. 

 

I feel that the icing up of the evaporator can be a big issue in cold weather and its not often talked about or at least the drop in performance is largely ignored.

[Onoff]

8 minutes ago, GrantMcscott said:

I am not looking for a Passiv house just a house that is comfrable and not extremly cold to live in. 

 

No offense but you're sort of missing the point. Having passive (or better) levels of insulation and airtightness are what leads to very low energy bills. Do it to current building regs requirements and you're already on a loser. Every compromise is lost heat.

 

As I always do I'll come back to Jeremy Harris's comment. Even with 300mm of EPS under his floor slab, 8% of his heat losses were through the floor. That's a continuous concrete slab with just a few service penetrations. 

 

There are then self builders on here who's houses aren't Passiv certified but have exceeded those specs. 

[GrantMcscott]

6 minutes ago, Onoff said:

 

No offense but you're sort of missing the point. Having passive (or better) levels of insulation and airtightness are what leads to very low energy bills. Do it to current building regs requirements and you're already on a loser. Every compromise is lost heat.

 

As I always do I'll come back to Jeremy Harris's comment. Even with 300mm of EPS under his floor slab, 8% of his heat losses were through the floor. That's a continuous concrete slab with just a few service penetrations. 

 

There are then self builders on here who's houses aren't Passiv certified but have exceeded those specs. 

I have not done it to  Passiv standard but have exceeded building regs standards.

Edited December 18, 2022 by GrantMcscott

[Onoff]

6 minutes ago, GrantMcscott said:

insulation wise the house has exceeded buiding regs.  

 

Do you have any details / pictures of the area where you had to compromise? Reading above it sounds like where the ends of the joists abut the wall there's a continuous missing airtight layer? That is a horrible problem to have. I think though someone on here did address similar, taping around the ends of every joist and possibly using an airtight paint. I'll try and dig the thread up. 

 

It sounds like a poor design unfortunately. 

[Redoctober]

23 minutes ago, GrantMcscott said:

The heating is Warmflow AS03-R32 downstairs there is UFH with 7 zones and 1 zone upstairs the controls are Emmeti TR3100.  Down stairs are all set to 20 oC from 06.30 to 20.30 and then they go down to 18oC.  

Wood burning stove is on all day from about 07.00 to 22.30 and all doors are open down stairs and this stops UFH coming on in other rooms as the are warm enough with weasther above 0oC.

 

 

You say the ASHP is costing you £40 a day and then on top of that you gave £20 being spent on wood. Well, I'm not that surprised to be honest if you are running a heating regime like you say you are. 7 zones for up to 14 hours and a wood burner on for 17 hours or so! 

 

How many people in the house and how large is the house? These factors need to be considered because given the heating schedule, the size of the house and number of occupants, you may find you are doing well out of it !

[GrantMcscott]

1 minute ago, Onoff said:

 

Do you have any details / pictures of the area where you had to compromise? Reading above it sounds like where the ends of the joists abut the wall there's a continuous missing airtight layer? That is a horrible problem to have. I think though someone on here did address similar, taping around the ends of every joist and possibly using an airtight paint. I'll try and dig the thread up. 

 

It sounds like a poor design unfortunately. 

Yes it where you say it is to late now as it is all plasterboarded and upstairs floor is down. 

 

It is not poor design it is a design that has not been followed and implimented.  I think the best I can get is sealing the skirtingboards and windows at best

[Ralph]

23 minutes ago, GrantMcscott said:

The heating is Warmflow AS03-R32 downstairs there is UFH with 7 zones and 1 zone upstairs the controls are Emmeti TR3100.  Down stairs are all set to 20 oC from 06.30 to 20.30 and then they go down to 18oC.  

 

Wood burning stove is on all day from about 07.00 to 22.30 and all doors are open down stairs and this stops UFH coming on in other rooms as the are warm enough with weasther above 0oC.

That seems like a hell of a lot of zones for a start unless your house is absolutely massive.

My house is not particularly airtight and we do notice the ASHP uses a bit more power on windy days.

It sounds like you have some significant air leaks so getting someone in for an interim test is probably money well spent. 

A wood burner going all day in a modern house, even one just meeting building standards, should have the house too warm if anything.

[ProDave]

37 minutes ago, Onoff said:

 

Does an MVHR compensate for a too airtight build?

With MVHR the better air tight the better.  It could be a completely hermetically sealed box and it would work well with MVHR

 

In Scotland if your air test is 3 or less, then you must fit MVHR, below 3 and trickle vents are not adequate.

[GrantMcscott]

3 minutes ago, Redoctober said:

 

You say the ASHP is costing you £40 a day and then on top of that you gave £20 being spent on wood. Well, I'm not that surprised to be honest if you are running a heating regime like you say you are. 7 zones for up to 14 hours and a wood burner on for 17 hours or so! 

 

How many people in the house and how large is the house? These factors need to be considered because given the heating schedule, the size of the house and number of occupants, you may find you are doing well out of it !

Hi

the house is about 270m2 to 300m2 and most of it open planned downstairs.

 

What should a typical heating regime be?

[Onoff]

1 minute ago, GrantMcscott said:

Yes it where you say it is to late now as it is all plasterboarded and upstairs floor is down. 

 

It is not poor design it is a design that has not been followed and implimented.  I think the best I can get is sealing the skirtingboards and windows at best

 

Surely the windows were sealed around? Are you meaning there's no Compriband/foam between window frame and structure or no airtight tape inside?

[MikeSharp01]

12 hours ago, Radian said:

The flipside of £40/day bills is the strain which that kind of energy demand puts on our generators and networks.

Everything is connected to everything else and not many people are thinking through the 1st order consequences let alone the second and third order unintended ones. We need to get our head in order so as to steer a path through this lot.

[GrantMcscott]

1 minute ago, Onoff said:

 

Surely the windows were sealed around? Are you meaning there's no Compriband/foam between window frame and structure or no airtight tape inside?

The windows were sealead with expandable foam all around where possible as for eample the one in the utility is siting on the frame so hard to get a seal to the bottom.  so it has a draught that needs to be fixed

[Redoctober]

2 minutes ago, GrantMcscott said:

Hi

the house is about 270m2 to 300m2 and most of it open planned downstairs.

 

What should a typical heating regime be?

 

Well that is a sizable house - I guess there is no "typical" heating regime, what I was trying to say is  - you pay for what you get.

 

My Mother in Law is a classic - she lives alone, wants all the lights on across the house and the heating on to the point you can walk around the house in a T shirt. Sadly, she fails to appreciate that that level of service comes at a cost!

[Radian]

10 minutes ago, GrantMcscott said:

the house is about 270m2 to 300m2 and most of it open planned downstairs.

 

43 minutes ago, GrantMcscott said:

The heating is Warmflow AS03-R32 downstairs there is UFH with 7 zones and 1 zone upstairs the controls are Emmeti TR3100.  Down stairs are all set to 20 oC from 06.30 to 20.30 and then they go down to 18oC.

 

Wood burning stove is on all day from about 07.00 to 22.30 and all doors are open down stairs and this stops UFH coming on in other rooms as the are warm enough with weasther above 0oC

 

How is the ground floor constructed? For all we know the UFH could be shorting to ground.

 

Of course it won't be but the first thing I noticed was setting the timer for 20^oC at 6:30  - which smacks of you expecting things to warm up by 7, when you fire up the woodburner.  The response time of UFH is going to be such that you'd come in and out of setback at a much earlier time.

 

Do you have a log of indoor temperature throughout the day?

 

I'm not so familiar with ASHP when used with UFH but it might be that people would even suggest having no setback at all.

[Onoff]

18 minutes ago, GrantMcscott said:

The windows were sealead with expandable foam all around where possible as for eample the one in the utility is siting on the frame so hard to get a seal to the bottom.  so it has a draught that needs to be fixed

 

Understood. Sadly all these little areas basically add up to one damn great hole in the airtight fabric was how someone here put it the other day. A great if sobering analogy. 

[GrantMcscott]

3 minutes ago, Radian said:

 

How is the ground floor constructed? For all we know the UFH could be shorting to ground.

 

Of course it won't be but the first thing I noticed was setting the timer for 20^oC at 6:30  - which smacks of you expecting things to warm up by 7, when you fire up the woodburner.  The response time of UFH is going to be such that you'd come in and out of setback at a much earlier time.

 

Do you have a log of indoor temperature throughout the day?

 

I'm not so familiar with ASHP when used with UFH but it might be that people would even suggest having no setback at all.

Slab with 150mm PIR then 40mm PIR covering the joints then UFH pipes and then 68mm screed.

 

no logs of indoor temp 

[Onoff]

22 minutes ago, GrantMcscott said:

The windows were sealead with expandable foam all around where possible as for eample the one in the utility is siting on the frame so hard to get a seal to the bottom.  so it has a draught that needs to be fixed

 

It's really not hard to get a seal there if the right product was used. The expanding tapes are great for this sort of thing. Expensive and you need your wits about you to use them. Sadly the average bodging builder will resort to foam, cheap foam at that and often after the event. 

 

Would it pay in the long run to have the windows removed and refitted?

[Radian]

3 minutes ago, GrantMcscott said:

Slab with 150mm PIR then 40mm PIR covering the joints then UFH pipes and then 68mm screed.

 

OK, that's a reasonable amount of insulation. I would expect it to take 4 or 5 hours to bring the room up a couple of degrees depending on floor finish. You really need a cheap temperature logger to see what's actually happening.

[JohnMo]

So walk us through the heat pump

 

Do you have a buffer, plate exchanger or low loss header, or are you connected direct to the heating system?

 

What is the flow temp out of the heat pump in heating mode?

 

What is the flow temp going into the floor?

 

Are all zones switched on or just one or two.

 

How long does the heat pump run for before switching off?

 

Edited December 18, 2022 by JohnMo
Missed word