Why the difference?

JabbaJibba

I have an old, (very old) oil heating system. It needs replacing, so I thought I'd look at air sourced heat pumps. I also have an open fire in the lounge as well as two radiators in there. I have had three quotes (well two quotes and an estimate).

One quote from British Gas advises that I change all my radiators (6), bathroom radiator/towel rail, and a kitchen plinth heater. The fire will need to be blocked. After the Government grant I'll pay just over £9k. Based on a Daikin 8.5kw system

The estimate was from an independent installer. They advised on similar location for the pump and cylinder. They advised that the plinth heater in the kitchen could stay, as could the bathroom towel rail, they estimated just over £8k. Only after paying £195 would they do a full survey where they may require changes to the fire status. I would get the £195 back if I purchased their system. Their system was based on a Mitsubishi pump.

Then I had Octopus, they advised the complete need for their tank to go in a different location. The plinth would have to go, but all the upstairs radiators could stay (three bedroom and the towel rail). They advised that the fire could stay if the lounge radiators were upgraded to K2 + K3 (BG advised of this radiator upgrade but stated the open fire needed to be blocked off or a burner put in it's place). Octopus are coming in at £4.5k! They are basing this on their own Octopus Cosy 9

Surely these guys are all using the same maths to work out the building heat loss. I appreciate there will be some technical difference in specs but this seems to be huge differences in what they are saying...can anyone shine a light as to why?

Netexporter

The Octopus Cosy heat pumps have a higher operating temperature, so more existing stuff can be re-used.

If I was paying for a survey, I'd spend £250 with Heat Geek.

This is the future of heat pumps!

JabbaJibba

The Octopus figure is for the lower temperature model, as I was looking at the longer term running costs.  In addition to that BG I have to arrange for the concrete pad for the pump to sit on. The independent can do the pad but will charge £500. Octopus the pad must be to their spec and is included in the price.

Netexporter

No idea, then. There does seem to be a fair bit of market adjustment, judging by a video I saw yesterday on replacing a gas boiler with an ASHP. Heat Geek prices have come down and Octopus have gone up, over the past year, to be in the same ballpark.

Are Heat Geek now CHEAPER Than Octopus Energy?

Netexporter

There's an update to that  last video.

Heat Geek's Zero Disrupt: How to Slash Heat Pump Cost & Chaos - YouTube

Exiled_Tyke

Plinth heaters for a gas/oil central heating system don't work with ASHPs as almost all the time the water is not hot enough to get fan to cut in.  Octopus told me that it needed disconnecting as it interferes with the system - which is advice I really am not sure about.   I did some research and found that some have changed the thermostatic switch on the unit to one that cuts in at much lower temperatures enabling it to still be used.  However I think even in the case you will need to disconnect it before Octopus install the ASHP (if you go with them) and then reconnect it up after they've gone. 

Exiled_Tyke

I think the rules on open fires/stoves changed.  At one time they had to go but no longer.  Octopus told me (two years ago) that mine would have to go but by the time of instal they weren't bothered about it and never mentioned it. However the ASHP has to be capable of heating the whole house, unsupported by the fire.   

They also told me that towel rails don't have to be upgraded according to the rules but that does mean accepting that the bathroom will not be adequately heated.   Ours is a little on the cold side in the depths of winter but certainly bearable . 

The table here shows the underperformance measured by Octopus from the towel rails.   The output (382W from two towel rails) is just over half what it should be (655W) in one bathroom and similar for the other bathroom (346W for a target of 692W) 

QrizB

Exiled_Tyke said:

I think the rules on open fires/stoves changed.  At one time they had to go but no longer.  Octopus told me (two years ago) that mine would have to go but by the time of instal they weren't bothered about it and never mentioned it. However the ASHP has to be capable of heating the whole house, unsupported by the fire.

My neighbour had a ASHP installed by EDF last winter. He was allowed to keep his solid fuel stove.

Agree that the ASHP will still be sized to heat the entire house, under reference weather conditions (which vary regionally), without assistance from the stove.

Netexporter

There was no question of removing my woodburner when I had my heat pump installed under the ECO4 scheme.

I would argue that an alternative heat source is vital in an area prone to frequent power cuts, like mine. 

matelodave

Netexporter said:

There was no question of removing my woodburner when I had my heat pump installed under the ECO4 scheme.

I would argue that an alternative heat source is vital in an area prone to frequent power cuts, like mine. 

Doesn't gas or even oil central heating stop working in the case of a power outage. Valves, pumps, control boards, fans and even thermostats need leccy to keep them going. Heatpumps aren't unique in that respect.

Exiled_Tyke

matelodave said:

Netexporter said:

There was no question of removing my woodburner when I had my heat pump installed under the ECO4 scheme.

I would argue that an alternative heat source is vital in an area prone to frequent power cuts, like mine. 

Doesn't gas or even oil central heating stop working in the case of a power outage. Valves, pumps, control boards, fans and even thermostats need leccy to keep them going. Heatpumps aren't unique in that respect.

Nextporter isn't singling ASHPs, just pointing out that more than one (non-leccy dependent) heat source is preferred.