ASHP - Investigations and calculations

[Fintray]

Having had my heat pump for a few weeks now I thought I'd give a bit of background and do a calculation of costs so far.

Our house is over 100yrs old built of stone but has had insulation added when rooms have been renovated and underfloor heating was installed when I removed the ground floor wooden suspended floor and replaced it with an insulated concrete slab. There are still quite a few draughty bits that still need to be tackled, the bathroom and utility rooms (both North facing) were always the coldest rooms in the house, quick to cool down!

When I did the heat loss calculations it showed a 9.33kW heat loss at -4.8 degrees and I had targeted a 35C flow temperature for the heat pump.
So a 10kW heat pump looked to fit the bill, a 250l HWC was added along with four larger K3 radiators and a large towel rail for the bathroom. There are still 5 radiators on microbore piping but all the new ones and towel rail are now 15mm.

Being a tight Scotsman buying heating oil was always a pain (though not when it was 10p/L) and would only run the heating for an hour in the morning and same in the evening, unless of course SWMBO said otherwise. Most days the WBS would be lit late afternoon to get some extra heat into the house.

As the heat pump needs to run for much longer than the oil boiler it was initially set to run from 6am to midnight then setback a couple of degrees from midnight till 6am, the initial heating curve was set at 0.6. The house was much much warmer than before so much so that SWMBO complained that it was too hot, WTF I wasn't expecting that! Since then the heating curve has been reduced 0.5, 0.45 and now 0.4 and is on weather compensation only. The heat pump has also been set to run without any night temperature setback, average living room temperature is 25C.

As I was too tight to run the oil boiler all the time to keep the house warm I've done the running cost calculation based on how much oil I would have needed to burn to give the same kWh's of heat.

So from the 9th to the 29th of March the heat pump supplied 2258kWh of heat and used 551.1kWh of electric giving a COP of 4.1.
I looked up the average price of electricity in the UK and it gave a price of 24.5p/kWh so multiplying that by 551.1 gives a cost of £135.02. Cost of heating oil (up here) was 67.56p/L (+5% VAT) during that period so if oil boiler was 80% efficient it would have cost 8.87p/kWh giving at total cost of £200.28 for the same 2258kWh and even if the oil boiler was 100% efficient it would have cost £160.09.

If I had been able to run the heat pump on electric at 7.5p/kWh the cost would only have been £41.33.
Over that 20 days my total electric import was 822.5kWh, if it had all been at 7.5p/kWh that would have cost £61.69 less Ripple rebate £13.65 and export credits £37.72 giving a total of £10.32 or 51p/day.

If I was Richbee I would look at a slightly smaller heat pump and some form of back up heating for the very coldest weather.

[Moxi]

Hi Andy, that’s the heating side, I need to factor in the DHW bearing in mind we have three kids under six and baths and showers is a daily regimen. We may not use much heating but the DHW is a more significant in my head at least.

Moxi

which is where SWMBO and I both get cross! It's OT, but part of the UK's energy transition ought to be realising that we just don't need (can't afford) to use so much energy and other resources, and IMO so-called "personal hygiene" has been fetishised, probably by the soap manufacturers' advertising agencies.
I nearly inherited the papier-mache bath which did me and my siblings as babies, except that it got used for mixing potting compost when it was clear that mum and dad's grandchildren weren't going to need it!

Our kids were "top and tailed" when tiny and bathed once a week, which generally continues to be our pattern now (not the top and tailing, obviously!) Hard dirty outdoor work means that one son does shower daily now, but I'm hoping that the other one doesn't waste water and electricity on the same fashion treadmill. Maybe our hygiene regime (which hasn't been criticised by friends) is why we are happy to have the house so much cooler than other people. (Since we got gas CH we don't have to get dressed under the bedclothes any more - which was normal in both our childhood homes, btw!)

There is a strong feeling that obsessive cleansing is leaving us vulnerable to bugs which our bodies should be happy to live in harmony with, indeed a healthy flora both outside and inside us is being recognised as a good way of stopping malevolent things getting a hold...
(sorry, about that, rant over!)
A

Sorry to have offended you.

Bye Everyone- it’s been fun till now.

[NoraBatty]

Ive not read the whole thread so apologies.

We moved in here, near turriff, in jan 2023
Moved from GCH to an ASHP, but rented in 2022-2023 with oil boiler.
Previous owner had it, plus solar plus IWI installednon a government eco grant.
I can only presume that they bang such things out so fast that quality does not factor into it.
So far the only things we have not found issues with are the heatpump itself, and the IWI.
We have a suspended wooded floor, with no insulation under it at all, and none of the ashp pipes are insulated properly. Either too thin insulation, or missing, or hanging off/gaping open all over.

We have a 12kwh heatpump, heat loss calcs apparently 18kw and despite finding many, many.many problems, and a flow rate currently at 12litres/min instead of the 24litre minimum, i am impressed.
One of the first things i did was rip out the old type thermostatic on/off zone controls.
I installed a heatpump management system (for want of the correct term) called homely, and manually overrode the zones (which have their own pathetic issues) to be open constantly, therfore making one whole house zone.
I did not hold out much hope for any good results, as i know how shoddy the install is, and how much insulation is still needed.
We are currently running on a scop of 4 also, which is not calculated from anything concrete.
Homely knows what heat has been produced, but assumes power usage is higher than it actually is based on assumptions of having 2 pumps and so on. following 1 seized pump (no inhibitor was put in the system by the installers ) i bypassed it, so this scop of 4 is actually higher.
I never bothered with keeping too close an eye on things, as i feel this year has been a waste of energy and money, as i have been chasing issue after issue with the system.

But still, i think the ashp is the way to go, especially with homely, which has constantly adjusted flow temperatures in response to the learned home environment. It even takes into account agile.
Im sure some of you have heard of it.

Anyway, our old gch used to be on 8am-10am, and 4pm-8pm. I work from home, so suffered the cold during the day in defiance of increasing bills. We heated to about 20C and were plagued with drafts.
Same with the oil heating.

Here, it is true what they say. The heat is different. There are no significant drafts, which keans we are very comfortable at 18C.
Homely has kept the house pretty much constant at 18C 24hrs in winter.
This has taken some adjustments on my part as i love sleeping with windows open. The colder the bedroom the better, and its why my OH sleeps in the spare room!
Knowing the ashp is on keeping constant temps, i have tried my hardest to adapt. I must say its nice getting up at 3am to use the bathroom now compared to having the window open.

Anyway, i sat down with the figures the other day.
in oil as renters, we used more kw than gas, but it was cheaper, ans worked out about the same price.
We are fully electric here, and if you take into consideration what electric prices are now, compared to 2 years ago when we left our old house, we are paying approximately £50 more a month in total for all of our elecric, dhw and heating, than we did on the south coast of england, just for heating and dhw and we are comfortable 24/7.

With a battery and more solar, investment into ripple, and the improvements to the ashp system i plan this year to get it functioning properly as it should have been designed, i am overjoyed, and convinced this homely thing has done its job tenfold.

We had no issue in the depths of winter last year or this year keeping the house nice and warm btw.
The only downside was having to pressurise the system so many times because of the shoddy work.
If ours can, yours will easily do the job, especially if correctly installed.

Sorry its long. Its been a journey.

[richbee]

Ive not read the whole thread so apologies.

We moved in here, near turriff, in jan 2023
Moved from GCH to an ASHP, but rented in 2022-2023 with oil boiler.
Previous owner had it, plus solar plus IWI installednon a government eco grant.
I can only presume that they bang such things out so fast that quality does not factor into it.
So far the only things we have not found issues with are the heatpump itself, and the IWI.
We have a suspended wooded floor, with no insulation under it at all, and none of the ashp pipes are insulated properly. Either too thin insulation, or missing, or hanging off/gaping open all over.

We have a 12kwh heatpump, heat loss calcs apparently 18kw and despite finding many, many.many problems, and a flow rate currently at 12litres/min instead of the 24litre minimum, i am impressed.
One of the first things i did was rip out the old type thermostatic on/off zone controls.
I installed a heatpump management system (for want of the correct term) called homely, and manually overrode the zones (which have their own pathetic issues) to be open constantly, therfore making one whole house zone.
I did not hold out much hope for any good results, as i know how shoddy the install is, and how much insulation is still needed.
We are currently running on a scop of 4 also, which is not calculated from anything concrete.
Homely knows what heat has been produced, but assumes power usage is higher than it actually is based on assumptions of having 2 pumps and so on. following 1 seized pump (no inhibitor was put in the system by the installers ) i bypassed it, so this scop of 4 is actually higher.
I never bothered with keeping too close an eye on things, as i feel this year has been a waste of energy and money, as i have been chasing issue after issue with the system.

But still, i think the ashp is the way to go, especially with homely, which has constantly adjusted flow temperatures in response to the learned home environment. It even takes into account agile.
Im sure some of you have heard of it.

Anyway, our old gch used to be on 8am-10am, and 4pm-8pm. I work from home, so suffered the cold during the day in defiance of increasing bills. We heated to about 20C and were plagued with drafts.
Same with the oil heating.

Here, it is true what they say. The heat is different. There are no significant drafts, which keans we are very comfortable at 18C.
Homely has kept the house pretty much constant at 18C 24hrs in winter.
This has taken some adjustments on my part as i love sleeping with windows open. The colder the bedroom the better, and its why my OH sleeps in the spare room!
Knowing the ashp is on keeping constant temps, i have tried my hardest to adapt. I must say its nice getting up at 3am to use the bathroom now compared to having the window open.

Anyway, i sat down with the figures the other day.
in oil as renters, we used more kw than gas, but it was cheaper, ans worked out about the same price.
We are fully electric here, and if you take into consideration what electric prices are now, compared to 2 years ago when we left our old house, we are paying approximately £50 more a month in total for all of our elecric, dhw and heating, than we did on the south coast of england, just for heating and dhw and we are comfortable 24/7.

With a battery and more solar, investment into ripple, and the improvements to the ashp system i plan this year to get it functioning properly as it should have been designed, i am overjoyed, and convinced this homely thing has done its job tenfold.

We had no issue in the depths of winter last year or this year keeping the house nice and warm btw.
The only downside was having to pressurise the system so many times because of the shoddy work.
If ours can, yours will easily do the job, especially if correctly installed.

Sorry its long. Its been a journey.

That sounds really promising, despite the install - good news

[Joeboy]

Having had my heat pump for a few weeks now I thought I'd give a bit of background and do a calculation of costs so far.

Our house is over 100yrs old built of stone but has had insulation added when rooms have been renovated and underfloor heating was installed when I removed the ground floor wooden suspended floor and replaced it with an insulated concrete slab. There are still quite a few draughty bits that still need to be tackled, the bathroom and utility rooms (both North facing) were always the coldest rooms in the house, quick to cool down!

When I did the heat loss calculations it showed a 9.33kW heat loss at -4.8 degrees and I had targeted a 35C flow temperature for the heat pump.
So a 10kW heat pump looked to fit the bill, a 250l HWC was added along with four larger K3 radiators and a large towel rail for the bathroom. There are still 5 radiators on microbore piping but all the new ones and towel rail are now 15mm.

Being a tight Scotsman buying heating oil was always a pain (though not when it was 10p/L) and would only run the heating for an hour in the morning and same in the evening, unless of course SWMBO said otherwise. Most days the WBS would be lit late afternoon to get some extra heat into the house.

As the heat pump needs to run for much longer than the oil boiler it was initially set to run from 6am to midnight then setback a couple of degrees from midnight till 6am, the initial heating curve was set at 0.6. The house was much much warmer than before so much so that SWMBO complained that it was too hot, WTF I wasn't expecting that! Since then the heating curve has been reduced 0.5, 0.45 and now 0.4 and is on weather compensation only. The heat pump has also been set to run without any night temperature setback, average living room temperature is 25C.

As I was too tight to run the oil boiler all the time to keep the house warm I've done the running cost calculation based on how much oil I would have needed to burn to give the same kWh's of heat.

So from the 9th to the 29th of March the heat pump supplied 2258kWh of heat and used 551.1kWh of electric giving a COP of 4.1.
I looked up the average price of electricity in the UK and it gave a price of 24.5p/kWh so multiplying that by 551.1 gives a cost of £135.02. Cost of heating oil (up here) was 67.56p/L (+5% VAT) during that period so if oil boiler was 80% efficient it would have cost 8.87p/kWh giving at total cost of £200.28 for the same 2258kWh and even if the oil boiler was 100% efficient it would have cost £160.09.

If I had been able to run the heat pump on electric at 7.5p/kWh the cost would only have been £41.33.
Over that 20 days my total electric import was 822.5kWh, if it had all been at 7.5p/kWh that would have cost £61.69 less Ripple rebate £13.65 and export credits £37.72 giving a total of £10.32 or 51p/day.

If I was Richbee I would look at a slightly smaller heat pump and some form of back up heating for the very coldest weather.

Brilliant read this, Nora's too.

"So from the 9th to the 29th of March the heat pump supplied 2258kWh of heat and used 551.1kWh of electric giving a COP of 4.1."

I continue to stand agog at the magic of heat pumps.

[Joeboy]

Hi Andy, that’s the heating side, I need to factor in the DHW bearing in mind we have three kids under six and baths and showers is a daily regimen. We may not use much heating but the DHW is a more significant in my head at least.

Moxi

which is where SWMBO and I both get cross! It's OT, but part of the UK's energy transition ought to be realising that we just don't need (can't afford) to use so much energy and other resources, and IMO so-called "personal hygiene" has been fetishised, probably by the soap manufacturers' advertising agencies.
I nearly inherited the papier-mache bath which did me and my siblings as babies, except that it got used for mixing potting compost when it was clear that mum and dad's grandchildren weren't going to need it!

Our kids were "top and tailed" when tiny and bathed once a week, which generally continues to be our pattern now (not the top and tailing, obviously!) Hard dirty outdoor work means that one son does shower daily now, but I'm hoping that the other one doesn't waste water and electricity on the same fashion treadmill. Maybe our hygiene regime (which hasn't been criticised by friends) is why we are happy to have the house so much cooler than other people. (Since we got gas CH we don't have to get dressed under the bedclothes any more - which was normal in both our childhood homes, btw!)

There is a strong feeling that obsessive cleansing is leaving us vulnerable to bugs which our bodies should be happy to live in harmony with, indeed a healthy flora both outside and inside us is being recognised as a good way of stopping malevolent things getting a hold...
(sorry, about that, rant over!)
A

Sorry to have offended you.

Bye Everyone- it’s been fun till now.

I remember vividly the water demands of a young family and the sheer horror of the teen years!

Nowadays it's more normal use. Strangely inverted as in the old days it was gas fired water heating massively contributing to our 32MWh gas bills. These days its all electric and a good chunk solar powered yet we use considerably less heated water.

Regarding personal hygiene. I worked a lot in the tropics and it was essential to shower daily if you wanted to feel even close to normal. Nowadays and with the advent of the outstanding Gillette ice 48hr deodorant I can shower every second day if I wish with no problems

I may have overshared there.