British Gas heat pumps - some restrictions on their offering FYI

[TonyT]

Can anyone let me know once the heat loss for a room is calculated  in watts how the kWh figure is calculated?

[JamesPa]

8 minutes ago, TonyT said:

Can anyone let me know once the heat loss for a room is calculated  in watts how the kWh figure is calculated?

It's essentially

 

heat_loss/deltaT * degreedays * 24

 

Heat loss in kW and answer in kWh.

 

Where deltaT=design temp of room minus outdoor temp (about 22 in the south east UK) and degreedays is the number of degreedays per year in the location (about 2000 in the UK).  24 is of course the number of hours in a day.

 

I'm not sure if MCS do any tweaks but that is the basic formula.

[Beelbeebub]

1 hour ago, JohnMo said:

Thermal store isn't any to do with any of the plans above, nice and simple for the boiler, just heat the cylinder, it doesn't care about anything other than the cylinder. But no use for the heat pump, as you need a second cylinder for DHW.

 

Do the individual zones call the boiler for heat, they should just call for a pump to start, to draw hot water from the store. The store thermostat does the calling for heat, independent of the heating system.

I honestly can't remember if the zones actuate the bolier direct.

 

Possibly not, because that would be mad.

 

I didnt have anything to do with the design of install of the system. It was done 20+ years ago by a now defunct company and pretty much all the documents have been lost. All I'm left with is a maze of wires that constantly trips the RCDs and a lot of leaks!

 

One day it will all be ripped out and it'll just be a single (or possibly per floor) zone on WC and a hot water cylinder possibly unvented. Then I can go back to worrying about something else other than how many times I have to go sort it out each winter.

 

Until then it plods on (ish)

[Archer]

Has anyone on here managed to get a detailed quote for an install from British Gas yet? Do they install radiators and central heating system as well as the heat pump... Will they do anything "out of the ordinary" (such as fan convectors?)

[markocosic]

I said "let's stop here" to avoid taking the piss / wasting any more of their time if they wouldn't install an unvented to my main.

 

Broadly though they have a recipe to work to. Everything must meet the specs in a backside covering way; for both the equipment AND the piping/emitters. He warned that they'd NEVER accept microbore and would want to repipe the lot even if the 10 mm was only the drops behind the plasterboard etc. I wouldn't expect anything remotely complex from them.

[JamesPa]

1 hour ago, markocosic said:

I said "let's stop here" to avoid taking the piss / wasting any more of their time if they wouldn't install an unvented to my main.

 

Broadly though they have a recipe to work to. Everything must meet the specs in a backside covering way; for both the equipment AND the piping/emitters. He warned that they'd NEVER accept microbore and would want to repipe the lot even if the 10 mm was only the drops behind the plasterboard etc. I wouldn't expect anything remotely complex from them.

Given this, I wonder how many '£3k standard installs' they actually do.

 

It sounds like none or thereabouts' because in practice the number of customers fitting their strict requirements must be minimal.

[sharpener]

21 hours ago, JamesPa said:

It sounds like none or thereabouts' because in practice the number of customers fitting their strict requirements must be minimal.

 

By coincidence have just had a call from "Tony" at EdF. He looked up the EPC and after the usual questions about construction and # of beds/baths he tells me they cannot quote because the solid walls mean the heat loss is too big for the largest HP in their range which is 22kW.

 

So I responded that as I have had 3 quotes for fitting a 12 or 15kW unit I thought their process was overly conservative and would lead to them unnecessarily ruling out a significant part of their target market - which he said he would pass up the chain.

[Beelbeebub]

Live scenes as Tony passes feedback up the chain.....