@jonathan

What was the heat loss calculation for your home?

Do you have a buffer tank or plate heat exchanger installed?

How is your heat pump being controlled, by thermostats and or TRV's?

Posted by: @jonathan

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original SAP report should be a 12 Kw/hr ASHP,

Should that read kW. kW is power and kWh is unit of energy used over time. 12kW used for a hour is 12kWh, also 4kW used for 3 hours is also 12kWh.

The SAP report will mention W, if you are reading kWh you are looking at the wrong thing.

Prospective of the SAP report you should have a heat loss calculation, done by the supplier. 

Welcome to the forums @jonathan.

There’s a lot to unpack with your case. First up, can you please remind us when your system was installed?

I must say, I’ve been battling the installer “customer” angle you’ve alluded to with the powers that be, and it’s a ridiculously frustrating situation homeowners find themselves in. In 2025, with MCS 2.0, some of this is apparently going to be addressed, but currently, consumer protections are undermined by the relationship between the installer and the consumer codes or MCS.

Do you also have an open case with MCS?

If possible, please can you give me an approximate timeline of the events you’ve mentioned above. Once I have more info, I’ll take this to MCS and other bodies for comment.

@johnmo subject to correction, I think Jonathan is saying their installer initially fitted a 7kW heat pump, but it should have been a 12kW unit.

@editor Hello Mars,

Thank you for your prompt reply.

The installer is a member of NAPIT, so I  made my complaint to them on 3rd July 24. They aim to respond in

10 working days (2 weeks). My case is being handled by Rebecca Riley who is currently on annual leave until

Monday 12th. She is waiting for a response from their Technical department.

I did start a complaint with MCS on 16/6/24 but did not proceed further. (Case # 110340)

My system was commissioned in March 21. Over the next year I had a number of visits from Vaillant mobile

engineers who all failed to mention that the ASHP was too small. The latest engineer pointed out that the

water tank was suitable for solar thermal but not solar thermal and ASHP. The installer took out a 400 ltr tank

and replaced it with 300 ltr with the same spec.

I have asked Ofgem whether I would loose my RHI payments if I change to a suitable size of pump and they

are unable to tell me. Their one object in life is to withdraw payments for RHI as often as possible with no

cause.

Regards

Jonathan

Posted by: @jonathan

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according to my original SAP repor

So how Watts does that specify you need in December or January?

@editor Hello

I am attaching the report from Amber Heating. 

I am intending to install approx 35 KW/hr of battery storage, which will be charged overnight at a cost of 7p

per Kw/hr. These will power the ASHP to heat  supply energy to the house during the day and evening. This

tariff is available for

EV users. I will pay 70% less for my energy.

Regards

Jonathan

@jonathan Regarding the battery storage enabling you to use grid supply when at the cheapest tariff rate, I do something very similar with 27 kWh of Tesla Powerwalls.

For anyone in my situation (EV tariff not available as we don’t drive due to both of us having a visual handicap) Octopus Energy Cosy works very well as they recently increased the amount of hours at the cheapest rate to 8 hours over 3 intervals in a day. They now charge approx. 11.2 pence per kWh during these 8 hours thus allowing for ‘topping up’ at more frequent intervals. My aim has been to only use the grid during these 8 hours and always have charge to power the domestic needs including an 8 kW Daikin ASHP. Regards, Toodles.

@derek-m 

Hello Derek

I have a 45L Vaillant buffer tank and sensoCOMFORT vaillant controlls plus 3 manifolds (one on each floor) controlled by time clocks (one each floor) plus room thermostats for each zone Kitchen hall office drawing room on ground floor, 4 bedrooms 1st floor, and bedroom and ensuite on top floor.

Regards

Jonathan

Do yourself a favour and give the heat pump some some chance of working well.

Time clocks delete 

Buffer delete

Room thermostats delete or set high they they only work to limit stop 

Set up loops by balancing to get the room temps correct, more flow if you need warmer, less flow to make rooms cooler 

Assume you have pumps & mixers on each UFH manifold? If so look to delete those.

Run pure weather compensation 24/7.

Required flow temp will drop considerably giving an automatic upping of heat pump output, make your radiator dual fuel to get higher output if needed.

Buy a couple of panel heater to backfill heat demand if needed