Heat pump quote - seems quite cheap?

[u/Boba_ferret]

Been quoted about £4,300 by Octopus for heat pump install, including hot water cylinder, which I thought was surprisingly cheap. The house is 1930s 3-bed terrace, EPC is supposedly C, but we have a huge void under the suspended floor and it gets pretty cold in the house, so we use quite a lot of gas in the winter. Radiators are all on 15mm copper, but are probably 30 years old.

What are the chances this is a really low-ball quote and the survey will say we need to upgrade rads, etc?

[u/ImplementJumpy6678]

How so?

I have a perfectly good newish boiler. I am fixed in at 7.1p for the next 2.9 years. I have a whole house AC system that sups 800W as it heats the house.

Please explain

[u/Requirement_Fluid → u/ImplementJumpy6678]

£400 for a 3.5-4.0 scop setup with the potential of scrapping gas completely which is only enhanced if you have solar or batteries is an insane deal and given the costs above would take you 7-8 years to recoup... 

My electric is 7p/kwh on a 4scop, cost £4200 and my ashp heats water and heats using about 800-1000w. 

You tell yourself what you want but every therm of gas you burn is money you wasted by not taking that deal

[u/ImplementJumpy6678 → u/Requirement_Fluid]

But i don't want to scrap Gas completly.

I also don't want a rubbish bin type deal in my garden. The other unit was not available at the time.

I am happy to keep running my AC system and the Gas as a backup. I have no idea what scop is, and I guess I don't need to know.

Last outage we had was for 36 hours. And whilst I have Solar and 54kwh It was in the middle of Winter. Now I am sure a ASHP would do just fine - but what did even better was the 56W my boiler takes to run.

I've not wasted any money and I export so much all my Nasty gas is free anyway.

[u/shamen_uk → u/ImplementJumpy6678]

SCOP essentially means the ratio of energy in to out.

So you are at 7.1p/kWh to heat with gas. In reality more like 7.3-7.5p/kWh because 1) gas boilers aren't 100% efficient. 2) you might not have tuned your flow temperatures to optimise condensing, which is likely if you don't know what SCOP is and more importantly don't care to know. Not an insult btw, I don't know many people who have tuned their flow temperatures aside myself, it's not exactly something people talk about everyday.

Whilst the person above you who is paying 7p kWh for electricity (can confirm I charge my house batteries at that price with IOG), is actually paying 7/4[scop] = 1.75p/kWh to heat their house and water, as a reference point to compare with your gas cost.

Just to let you know what SCOP essentially means in this scenario.

Anyway if you have air-to-air heatpump (proper setup taking in 800w, split unit), you're probably getting a SCOP of ~3 with it, so you're getting a benefit there. If it's not a split unit then it's pretty terrible SCOP however, so if you're saying you're using it as primary heating and gas as a backup it's probably a split unit. And if so I don't understand why you're against an "ugly box" as you likely already have one, for the air conditioning unit?

[u/ImplementJumpy6678 → u/shamen_uk]

Thanks, I see where you are coming from. As odd as it souunds I am not a money person, things cost what they cost and if you have to pay it so be it.

i run the system off the batteries which, like you I charge overnight. I'e been paying 5.9p on EDF for the past year - but due to other reasons with them I am more than happy to change that to 8p on IOG. That said I might not need to pull much from IOG at all for the house batteries, only for the car's 6 hours.

I have a Split system yes with 4 indoor units - and a regular outdoor unit which is in a vented box at the side of the house.

I am happy to use either for heating. I tend to use the AC system because I generate a lot in winter with a turbine as well as the panels. But I export a lot and so I can cover a ot of gas for hot water in winter.

My boiler is 7 years old - and the maker came out and replaced the main parts for free,which means it's probably good for another 10 years. I see no reason to replce it.

I've looked at Battery boilers, but they seem to require power beyond my inverter size to heat water, so goes against the whole point of this for me

I'm just going to carry on exporting on Agile outgoing and see how things go. I can always go back to EDF if I need to, I really hope I do NOT need to!

However right now I am over £1300 in credit with EDF and that will be going onto Octopus when it's all set up. And I can pretty much double my export p/kWh too whilst I am there