Heat Pumps: anyone have one/thought about it?

[200sols]

I do agree. In the 90s a lot of the plumbing in larger estate builds went to crap, 8mm microbore saved pennies, 75mm cavities (when winters were colder!) etc.... Makes difficult to update buildings.

We are building our own house now, and self builders require more stringent efficiency make-up than Taylor Wimpy, Redrow etc... despite these guys having huge economies of scale. They should be held to a higher standard than individuals, but it will never happen!

All the houses around here built in the late 90s have uninsulated cavities, some people have added it and some have had it removed due to it causing problems. Houses of that era seem to have higher frontloaded costs for getting onto a heat pump.

You are absolutely right on the second point as well, makes no sense. You would have hoped this gov would be closing that gap but it doesn't look to be happening.

 

[b0rn2sk8]

I do plan to get solar and battery storage but not for 2-3 years.

I'm on a fixed tariff until sept with no time of use periods.

Currently paying 22.44p for electric and 5.5p for gas

It really just depends of you want to seize the opportunity to move over when it’s £500. I can’t see it getting any cheaper put it that way.

P.S. if you have the money, install solar ASAP. We really are in a golden age right now, costs really are as low as I have ever seen. Panels are as cheap as I can ever seeing them getting and batteries are getting cheaper. On the flip side the cost to have them installed isn’t getting cheaper (e.g. wages for trades) so I can’t see the overall cost dropping much more.

 

[The Angry Welshman]

octopus has given me an online quote of £1800 after grant...... they now want £200 to do full survey and start the journey

 

[b0rn2sk8]

The £200 gets knocked off the £1800 final price and is refundable if you don’t go ahead.

 

[Hyburnate]

octopus has given me an online quote of £1800 after grant...... they now want £200 to do full survey and start the journey

That's slightly stomachable, I got an online quote of £7500 (incl the grant)

For what it's worth, it's a 3 bed victorian semi... not sure if a ASHP is best suited really but thought it was worth a look, my boilers got loads of life left in it but gas prices shan't be getting cheaper!

 

[The Angry Welshman]

The £200 gets knocked off the £1800 final price and is refundable if you don’t go ahead.

i may look at it closer come the summer..... not got the desire right now as other things taking priority

 

[reef]

So I've been looking into this more and have been trying to work out two things: 1. Whether we can fit a hot water tank in the airing cupboard and 2. What it might cost per year to run (worst case).

The airing cupboard is 850mm x 650mm x >2000mm and currently houses our combi boiler. I know Octopus do a slimline tank, but they can be pretty strict on the 1m x 1m x 2m dimensions. I am not too concerned if they need to put other things in the loft, but as our loft already contains 165kg of batteries, I don't like the idea of any more heavy items up there so would not want the tank up there. We have electric showers and only use hot water for the sinks and the occasional very shallow bath for the kids, so we don't need a huge capacity tank.

The location of the heat pump is also a consideration. The perfect spot would be against the wall on the other side of the house to where the boiler currently is. That would involve an approx. 8.7m run through the loft and then down and out around 4.8m to the heat pump if it were to be located there. The consumer unit is also on the other side of the house, so a cable run would be needed too (not to mention another sub-unit).

Cost wise to run, we use about 7200kWh of gas for heating and hot water per year. This is almost identical to what our EPC says (B 86) - approx. 7100kWh. We live in a 2019 new build which is extremely well insulated. Assuming the boiler is 95% efficient, that's 6840kWh of heat. Assuming a rough COP of 3.5, that's 1954kWh of electricity. We're on Intelligent Octopus Go EV tariff, so get 6 hours at 6p/kWh and the other 18 hours at 25.045p, so that would be an average 20.28p over the 24 hours. That would be £396 per year vs £454 for gas - we would only require a COP of 3.0 to break even. This is worst case and does not take into account that we have a 14.7kWh battery and 9.42kW of solar, so it would be substantially less in reality. We could eventually also go induction hob and remove the gas altogether, saving the £108 standing charge per year.

I did a test yesterday running the combi at 50C to see how the house temperature faired and it did struggle a little but did eventually get to temperature, so I imagine we'd need a few radiators replacing, but nothing drastic. The quote suggests Octopus will do this. We're on the standard plastic 10mm OD piping to the radiators so not ideal, but pretty standard for new builds.

I think for the quoted £600 installation cost it's worth it for us. The wife likes the idea of the house being a constant temperature so is in favour too. The big question mark is the hot water tank. I guess the only way to know is to have the survey.

 

[alphaomega16]

I inquired about heat pump with octopus and they wanted money before doing a survey but said if I wasn't happy to go ahead id get the money back, seems like a lot of hassle instead of just coming out to do the survey without the faff of paying/refunding etc etc.

 

[200sols]

I inquired about heat pump with octopus and they wanted money before doing a survey but said if I wasn't happy to go ahead id get the money back, seems like a lot of hassle instead of just coming out to do the survey without the faff of paying/refunding etc etc.

The surveys are quite involved and take a bit of time. Its probably a good way for them to weed out the time wasters.

 

[magicoi]

That's slightly stomachable, I got an online quote of £7500 (incl the grant)

For what it's worth, it's a 3 bed victorian semi... not sure if a ASHP is best suited really but thought it was worth a look, my boilers got loads of life left in it but gas prices shan't be getting cheaper!

You did well! I got a quote of £18,500 before the grants deduction following a visit and heat loss survey & a similarly priced seperate online 'quote' via HeatGeek!! 4 bed detatched, circa 15 years old!! As you can imagine, thats not going to happen so I think ill just replace the oil boiler for a new condensing one and see where the tech is in 15 years time!

 

[Hyburnate]

You did well! I got a quote of £18,500 before the grants deduction following a visit and heat loss survey & a similarly priced seperate online 'quote' via HeatGeek!! 4 bed detatched, circa 15 years old!! As you can imagine, thats not going to happen so I think ill just replace the oil boiler for a new condensing one and see where the tech is in 15 years time!

I mean yeah that’s not great. It was £17,500.

My gas bill for last week was around £50. I’m going to tweak my heating setup this weekend and wire in OpenTherm I think!

 

[b0rn2sk8]

So I've been looking into this more and have been trying to work out two things: 1. Whether we can fit a hot water tank in the airing cupboard and 2. What it might cost per year to run (worst case).

The airing cupboard is 850mm x 650mm x >2000mm and currently houses our combi boiler. I know Octopus do a slimline tank, but they can be pretty strict on the 1m x 1m x 2m dimensions. I am not too concerned if they need to put other things in the loft, but as our loft already contains 165kg of batteries, I don't like the idea of any more heavy items up there so would not want the tank up there. We have electric showers and only use hot water for the sinks and the occasional very shallow bath for the kids, so we don't need a huge capacity tank.

You’ll need to talk to your surveyor about this. They can put the buffer in the loft no problem.

I wouldn’t skimp on the tank, make sure you get something that can also be used for showers. Trust me, mains pressure hot water blows an electric shower away and I’d fully recommend the upgrade when you next fancy doing some renovation work.

You could always get the structural calcs done for the loft and if it will go in there you gain a very useful cupboard in your house.

The location of the heat pump is also a consideration. The perfect spot would be against the wall on the other side of the house to where the boiler currently is. That would involve an approx. 8.7m run through the loft and then down and out around 4.8m to the heat pump if it were to be located there. The consumer unit is also on the other side of the house, so a cable run would be needed too (not to mention another sub-unit).

Should be fine, functionally there isn’t a limit, it just adds to the heat loss.

Cost wise to run, we use about 7200kWh of gas for heating and hot water per year. This is almost identical to what our EPC says (B 86) - approx. 7100kWh. We live in a 2019 new build which is extremely well insulated. Assuming the boiler is 95% efficient, that's 6840kWh of heat. Assuming a rough COP of 3.5, that's 1954kWh of electricity. We're on Intelligent Octopus Go EV tariff, so get 6 hours at 6p/kWh and the other 18 hours at 25.045p, so that would be an average 20.28p over the 24 hours. That would be £396 per year vs £454 for gas - we would only require a COP of 3.0 to break even. This is worst case and does not take into account that we have a 14.7kWh battery and 9.42kW of solar, so it would be substantially less in reality. We could eventually also go induction hob and remove the gas altogether, saving the £108 standing charge per year.

Your gas boiler definitely isn’t 95% efficient regardless is what the sticker says, however you’ll probably run the house slightly warmer on average than you otherwise would with the boiler because it will be cheaper per kWh to run.

But given you have solar, batteries and time of use, you’ll save some money either way. Gas can’t compete when you are paying below the going rate for electricity.

I also really rate induction hobs, they work very well but it does mean you can’t use cheap aluminium pans and the aluminium pans that claim to be induction compatible because they put a thin bit of steel on the bottom are not great either.

I did a test yesterday running the combi at 50C to see how the house temperature faired and it did struggle a little but did eventually get to temperature, so I imagine we'd need a few radiators replacing, but nothing drastic. The quote suggests Octopus will do this. We're on the standard plastic 10mm OD piping to the radiators so not ideal, but pretty standard for new builds.

I’d expect then to want to swap your reception rooms and bedrooms as a minimum.

I think for the quoted £600 installation cost it's worth it for us. The wife likes the idea of the house being a constant temperature so is in favour too. The big question mark is the hot water tank. I guess the only way to know is to have the survey.

Yup, pretty much.

See my comments about the tank above. I wouldn’t write off the loft either, the extra space in the house is more useful.

 

[reef]

You’ll need to talk to your surveyor about this. They can put the buffer in the loft no problem.

I wouldn’t skimp on the tank, make sure you get something that can also be used for showers. Trust me, mains pressure hot water blows an electric shower away and I’d fully recommend the upgrade when you next fancy doing some renovation work.

You could always get the structural calcs done for the loft and if it will go in there you gain a very useful cupboard in your house.

Should be fine, functionally there isn’t a limit, it just adds to the heat loss.


Your gas boiler definitely isn’t 95% efficient regardless is what the sticker says, however you’ll probably run the house slightly warmer on average than you otherwise would with the boiler because it will be cheaper per kWh to run.

But given you have solar, batteries and time of use, you’ll save some money either way. Gas can’t compete when you are paying below the going rate for electricity.

I also really rate induction hobs, they work very well but it does mean you can’t use cheap aluminium pans and the aluminium pans that claim to be induction compatible because they put a thin bit of steel on the bottom are not great either.

I’d expect then to want to swap your reception rooms and bedrooms as a minimum.


Yup, pretty much.

See my comments about the tank above. I wouldn’t write off the loft either, the extra space in the house is more useful.

The airing cupboard where it would go is more like 2.2m high, so the limit is more on the diameter of the tank and whether Octopus would install it there. I have heard of them installing in airing cupboards smaller than ours, but they're a more difficult install, so it just depends how keen they are. As long as the main tank can go in there, I'm not fussed about any other stuff going up in the loft. Point taken on the tank size. A shower using the current 8kW electric unit is already a good 1.5kWh of electricity usage there or thereabouts. I'm betting you could probably heat a full 210 litre tank with a heat pump for not far off that. Definitely something to think about.

Good to know there's no issues with the pipe run length from tank to heat pump. Funnily enough, we already have a split air conditioning with the outside unit located next to where I would like the heat pump, so I at least know there would be no issues having it there.

The rough calculation was based on best case for the current combi and worst case for the heat pump (hence ignoring the solar/battery). At least even in this scenario its cheaper.

I was thinking the same aswell with the radiators. The upstairs bedroom radiators especially are woefully undersized even now for the combi.

I think I'll have a discussion with the wife and look at booking it in.

 

[b0rn2sk8]

For anyone who has an octopus heat pump (or are in the process of getting one) and are thinking of solar, Octopus are sending out the below:

We love seeing you embrace your super-efficient, super-green heat pump to save money and reduce your carbon footprint. So we thought you might be interested in taking it to the next level: powering it with your very own solar and battery.

And, as one of our valued heat pump heroes, we're offering you an exclusive 10% discount on a solar and battery installation – that's around £1,000 off the price of our most popular setup which costs £10,200.

Edit: offer terms:

• 10% will be discounted from eligible solar and battery orders placed before 30th March 2025.
• The installation must be carried out by Octopus Energy.
• The discount will be calculated from the final cost of your solar and battery system and will be applied to the price detailed in your installation agreement. It won’t be applied to your initial online quote.
• The discount cannot be used in conjunction with any other offer.

 

[jpaul]

The rough calculation was based on best case for the current combi and worst case for the heat pump (hence ignoring the solar/battery). At least even in this scenario its cheaper.

is 3.0 the worst case cop for winter time scenario, was wondering if you might have divided the energy consumption for modelling(spreadsheet simulation) into seasons, incorporating historic gas monthly;
even though cost is offset by solar/time-shift battery input.

combi-boiler/airing-cupboard is on the upper floor ? will it have the pressure if you do later use it for showers, or is it worth anticipating a pump (as I'm doing, even though we have a potential airing cupboard/tank room on 2nd floor, above combi in kitchen).Shower at 7l /min can burn through 40L of 50c water - so is 200L adequate for family, with hot water needs for meal prep too.

 

[b0rn2sk8]

The installer will give you an estimated energy use based on a typical year in the U.K. based on the MCS formula.

You can’t fit a pump to an unvented cylinder, they operate at mains pressure so it doesn’t need it anyway. There isn’t a material pressure loss going from first to second floor unless your plumbing is stupid.

MCS guidelines dictate how big the cylinder should be, it’s based on number of bedrooms. https://mcscertified.com/wp-content/uploads/2019/08/Domestic_HW_cyl_selection_guide.pdf

How much hot water you actually use depends on the temperature of the cylinder, the hotter it is, the more energy it contains. Typical shower temperature is 37-39C, typical incoming cold water temperature is above 10C so you are mixing 50c water down to 38 with 10C water 1L out the shower is well below 1L out the tank.

Your temperature probe is at the bottom of the cylinder, the water at the top of the tank is more like 55C.

 

[Kol]

Thinking of going with the heat pump, octopus quoted £700ish which I think is reasonable. House built in 2014, 4 bed detached, seems well insulated. I’m not sure I like the look of the cosy so hoping I can push for the Daikin.

Reading through, any issues with placement? Ideally I’d not want it right outside where the boiler currently is, it could can go there but I’d prefer it a bit more out of the way.

 

[-Ad-]

For anyone who has an octopus heat pump (or are in the process of getting one) and are thinking of solar, Octopus are sending out the below:




Edit: offer terms:

What kit are Octopus offering for a £10,200 solar system?

From what I've seen it'll be a £6000 system from a local or specialist solar installer, with a large markup for Octopus.

 

[b0rn2sk8]

What kit are Octopus offering for a £10,200 solar system?

From what I've seen it'll be a £6000 system from a local or specialist solar installer, with a large markup for Octopus.

No idea, they just quoted the average install cost. They would give you a specific quote.

 

[bimbleuk]

The airing cupboard where it would go is more like 2.2m high, so the limit is more on the diameter of the tank and whether Octopus would install it there. I have heard of them installing in airing cupboards smaller than ours, but they're a more difficult install, so it just depends how keen they are. As long as the main tank can go in there, I'm not fussed about any other stuff going up in the loft. Point taken on the tank size. A shower using the current 8kW electric unit is already a good 1.5kWh of electricity usage there or thereabouts. I'm betting you could probably heat a full 210 litre tank with a heat pump for not far off that. Definitely something to think about.

Good to know there's no issues with the pipe run length from tank to heat pump. Funnily enough, we already have a split air conditioning with the outside unit located next to where I would like the heat pump, so I at least know there would be no issues having it there.

The rough calculation was based on best case for the current combi and worst case for the heat pump (hence ignoring the solar/battery). At least even in this scenario its cheaper.

I was thinking the same aswell with the radiators. The upstairs bedroom radiators especially are woefully undersized even now for the combi.

I think I'll have a discussion with the wife and look at booking it in.

I had more than one surveyor and the second was more experienced so called my installer to confirm they would use my 1m x 1m x 1.5m airing cupboard. The tank was increasing from 90L to 150L however which is quite small for a ASHP install. Bigger tanks help with the SCOP/COP as the larger mass of water keeps heat longer.

Annoyingly because my airing cupboard was over a stairway Octopus required a structural survey so as it's £500-700 I made sure the that surveyor did the loft tank support structure as well. I then agreed with the installer that visited later that the loft was actually a better location due to standing room and the existing 140L of stored water.

Downside was that the installer was not confident about getting a slim tank through my loft hatch so I agreed to enlarge it. I did that myself added extra support and boarding where the engineers would be working. I will regain two sizeable storage spaces though.

If you search on Youtube for Cosy 6 you will see the Nicolas Raimo's install which I believe has 34m of piping!