ASHP Costing £40 a day and cold upstairs

[GrantMcscott]

Hi

We are currently spending £40 a day on electricity with our ASHP and lighting etc but also spending £20 on wood and coal for heating.  

 

What is the best way to find the issues drafts and cold spots so i can fix them.  The house still need rtedering and cladding done outside but windows and doors can not be sealed propperly

 

Is a theremal imnaging camera the best way to go if so what is the most economical one to buy or rent

 

Any advice would be great to reduce running costs

[Mr Punter]

It has been exceptionally cold for a few weeks and it seems that heat pumps do not do well with this.  I imagine the efficiency drops a great deal as there have been loads of posts over the last couple of weeks from heat pump owners crying about their energy costs.

 

I suspect that it will ease up soon and the running costs will drop a good deal.

 

Did you have an airtightness test?  That seems to be a decent way of working out if you are leaking lots of air but you need the doors and windows properly sealed first.

[GrantMcscott]

1 minute ago, Mr Punter said:

It has been exceptionally cold for a few weeks and it seems that heat pumps do not do well with this.  I imagine the efficiency drops a great deal as there have been loads of posts over the last couple of weeks from heat pump owners crying about their energy costs.

 

I suspect that it will ease up soon and the running costs will drop a good deal.

 

Did you have an airtightness test?  That seems to be a decent way of working out if you are leaking lots of air but you need the doors and windows properly sealed first.

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

[Declan52]

The cheapest way too find draughts is to walk round with a candle and go up and down each junction in the floor, ceilings round light fittings, wall sockets, windows and doors and see where the flame moves. Very low tech but it works. 

[Kelvin]

When you say you aren’t ready for the air tightness test what do you mean? Didn’t you do one before the final fit out? 

[ProDave]

Earry in the build I set up my own blower door, made from an old desk fan, some OSB, some cardboard and a lot of duck tape, set up to suck air out of the house so it was easy to go around to find air blowing into the house and seal up all the leaks.  Best done before the plasterboard goes on.

 

Yes there are indeed a lot of people worrying about costs but what we don't know is how much of that cost is "because" it is an ASHP and how much of that cost would still be there if the same house was heated with a gas boiler?  to counter this, there are also several of us hapilly using an ASHP up here in the far north where this last 2 weeks weather is just a normal cold spell that we get most winters.  My last weeks ASHP usage for heating  was 110kWh so about £33 for the weeks heating and it did not stop working when it was nearly -10.  It was also not my most expensive week either, we had colder and more expensive about 2 years ago.

[GrantMcscott]

3 minutes ago, Kelvin said:

When you say you aren’t ready for the air tightness test what do you mean? Didn’t you do one before the final fit out? 

We have plasterboarded and kitchen is in and some bathroomes but no carpets and some walls still need to be taped ect.  When is the right time to do an air test?

[Kelvin]

You also need to average it out across the year not base your costs on the coldest week of the year. 

[Radian]

32 minutes ago, GrantMcscott said:

Is a theremal imnaging camera the best way to go if so what is the most economical one to buy or rent

 

 

Flir One for Android smartphones for £221 is the lowest cost thermal imager I know of. If you get one you'll find it incredibly handy for all sorts of things. I've been mapping out the location of my CH pipes as well as finding air leaks:

 

[GrantMcscott]

6 minutes ago, ProDave said:

Earry in the build I set up my own blower door, made from an old desk fan, some OSB, some cardboard and a lot of duck tape, set up to suck air out of the house so it was easy to go around to find air blowing into the house and seal up all the leaks.  Best done before the plasterboard goes on.

 

Yes there are indeed a lot of people worrying about costs but what we don't know is how much of that cost is "because" it is an ASHP and how much of that cost would still be there if the same house was heated with a gas boiler?  to counter this, there are also several of us hapilly using an ASHP up here in the far north where this last 2 weeks weather is just a normal cold spell that we get most winters.  My last weeks ASHP usage for heating  was 110kWh so about £33 for the weeks heating and it did not stop working when it was nearly -10.  It was also not my most expensive week either, we had colder and more expensive about 2 years ago.

our electricity bill last week was £200 so need to address this and find out where we are loosing heat 

[nod]

We’ve been warned to expect 30% higher running costs than our gas boiler and by the guys that sell them 

 

The problem with HPs is they are often sold as a cheap way of heating your home 

Most people that are swapping over retrospectively have no idea that there bills will be higher 

 

 

 

[GrantMcscott]

14 minutes ago, nod said:

We’ve been warned to expect 30% higher running costs than our gas boiler and by the guys that sell them 

 

The problem with HPs is they are often sold as a cheap way of heating your home 

Most people that are swapping over retrospectively have no idea that there bills will be higher 

 

 

 

I got told it would be more expensive but did not think it would be 5hat much would be cheaper with oil

[Radian]

16 minutes ago, nod said:

We’ve been warned to expect 30% higher running costs than our gas boiler and by the guys that sell them 

 

 

That's the first time I've heard that being said. I'm shocked.

[JohnMo]

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.

 

Gas boiler at low flow temps so a like for install should give a system efficiency of about 97% (that is what is currently running at).

 

So a heating day uses 100kWh (nice round number) going in to the floor.

 

Gas 100 / 0.98 =102 kWh Cost = 9.78p kWh = £9.97, plus standing charge of 27p = £10.24

Electric 100 /3.4 = 29.4 kWh Cost = 33.068p kWh = £9.72

 

So gas is slightly more expensive but pretty close

 

But at 7 degrees instead of -7 the CoP goes up to 5 at the same flow temp, so costs reduce for electric by 32%, then gas wins by a good margin.

 

A poor install costs you more (45 degree flow the CoP drops to 2.4, so cost 30% more to run).  A good one can cost you less.

Edited December 17, 2022 by JohnMo
added details about 45 flow temp

[Redbeard]

@GrantMcscott said: "We have plasterboarded and kitchen is in and some bathroomes but no carpets and some walls still need to be taped ect.  When is the right time to do an air test?"

 

I think I'd do it now. I would have suggested doing it before the kitchen was fitted and arguably before the plasterboards went on - when the main envelope was tight but before you'd added enough stuff to get in the way if you found leaks. You mention taping. Are you just joint-filling or full wet plastering on plasterboards? What is the house built of? If it's masonry do tell us it's not dot-and-dabbed plasterboard... please.

 

 

[GrantMcscott]

22 minutes ago, Redbeard said:

@GrantMcscott said: "We have plasterboarded and kitchen is in and some bathroomes but no carpets and some walls still need to be taped ect.  When is the right time to do an air test?"

 

I think I'd do it now. I would have suggested doing it before the kitchen was fitted and arguably before the plasterboards went on - when the main envelope was tight but before you'd added enough stuff to get in the way if you found leaks. You mention taping. Are you just joint-filling or full wet plastering on plasterboards? What is the house built of? If it's masonry do tell us it's not dot-and-dabbed plasterboard... please.

 

 

Timber frame with 140 frametherme 40. Then air barrier then 25 mm pir.  40mm cavity then 15mm plasterboard

[Roger440]

Why a cavity behind the plasterboard

 

I'll put my money on air circulating behind the plasterboard. 

[Redbeard]

Thanks for that. Well, provided the air-barrier has been well detailed at all joints, perimeters and penetrations you may hopefully have a good air-tightness envelope. Were all the windows and doors well taped in?

[Redbeard]

"Why a cavity behind the plasterboard

 

I'll put my money on air circulating behind the plasterboard."

 

Service void, and yes, if the air barrier is poorly detailed you could be right, but with fingers crossed it could be tight as a drum.

[GrantMcscott]

4 minutes ago, Redbeard said:

"Why a cavity behind the plasterboard

 

I'll put my money on air circulating behind the plasterboard."

 

Service void, and yes, if the air barrier is poorly detailed you could be right, but with fingers crossed it could be tight as a drum.

All the pir was taped to make sure no air.  Put could be poorly fitted air barrier

Edited December 17, 2022 by GrantMcscott

[HughF]

What make and model of Ashp, and how is it installed/controlled? This could just as easily be a controls/installation problem instead of a heat loss problem.

[Bozza]

@GrantMcscottwhat is your daily KW useage for the ASHP and for the rest of your electricity.  As a opposed £cost as that is a difficult thing to assess due to varying tariffs and high current tariff v locked in lower tariffs.  eg I’m expecting my costs to double next year but purely down to tariff cost not that the system is inefficient.

what is the EPC on your house.

what is the sqm size of your house.

are you happy that your settings are good and you are running the system effectively.

 

[SteamyTea]

3 hours ago, GrantMcscott said:

We are currently spending £40 a day on electricity with our ASHP and lighting etc but also spending £20 on wood and coal for heating.  

How large is your unfinished house?

The exposed surface area is important as well.

 

I know people that are spending £40/day of direct electric heating, it is nice sitting around their houses because they are 8°C warmer than my place.

 

[Radian]

I'm beginning to wonder how all this is going to impact on our energy security. The flipside of £40/day bills is the strain which that kind of energy demand puts on our generators and networks.

[SteamyTea]

7 minutes ago, Radian said:

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

Does not seem to be ridiculously high generation this week.

 

Not sure that the dip on Thursday was, was that when Scotland and the Isles went caput?

Or misreportting.