ASHP turning out to be very expensive

[Venkat Rangala]

Hi,

I badly need some help / suggestions asap.

Mine is a 5 bed semi house (tbh its not massive as bedrooms 3 & 4 are box rooms & the 5th one is loft room)

I got 20 Solar panels already on the roof (installed May 2022).
I got underfloor heating on the ground floor and standard radiators upstairs powered by gas boiler, all was working well without problems.
Then I got this idea (terribly bad) of getting heatpump and replace my gas boiler. I got this done with Omni Heat&Power in Aug 2022.

I was of the impression that my bills will be <£200 per month.
The underfloor seems working well, but the upstairs is not getting any heat at all. The radiators are always cold. But my electric bill sky rocketed to £600+

Unfortunately for me Omni Heat&Power gone bust in Nov 2022. And I am left with not much help.
There is a 50K insurance something, I spoke to iwa.biz (insurance guys). I was told to get someone to check the system and give a quote for what needs doing to rectify.

I am totally lost and struggling.
Any help / pointers on this please.
Also want to know if I can use my solar batteries to source the heatpump. (I was of the impression it was done that way, but I doubt)

I just checked and noticed that it is costing 1KWH in 30minutes

 

Are there any contacts who can provide me in and around Berkshire (I am based in slough), who can help me on this.

Also attaching the pics of my installation, if it can give some idea what could be wrong.

 

1. Grant small box for the settings (11 & 12th pic)
2. one motor of some sort below the kitchen sink(13th pic). This one turns on when ever it lies and costing me electric bill.

 

Apologies for the long post

Thank you
Venkat

[Dave Jones]

all that info is great but not really of any use.

 

What is your heat loss calculation ?

[ProDave]

That looks like a big heat pump so presumably an old house not much insulation?

 

Did they do any heat loss calculations before quoting?

 

All thermometers are low so presumably turned off when you took the photographs?

 

What are we supposed to be looking at in the last picture?

 

The general install looks reasonable, some more pipe insulation would be a good idea but I doubt that on it's own would account for the high bills.

 

How much were you previously paying for gas? That is the best indicator what your running costs might be.

[SteamyTea]

You really need to know the heat losses of the building.

This is not difficult to calculate, just tedious getting all the right info.

 

You say the UFH is working, but the radiators upstairs are not.

This could be as simple as a valve not opening.

You also say the the bill has gone up to £600/month. That is very worrying, but to be honest a gas bill of £200/month seems high.

Do you have any idea how much insulation there is under the floor? You could be loosing vast amounts of energy there.

[JohnMo]

Your cylinder thermostat photo 2 is set high, it is likely your heat pump will struggle to get up to that temperature and will keep trying using loads of energy. Turn down to high 40s.

 

Do you electric immersion in buffer and cylinder are these programmed to come on at any point.

 

Call Grant heat pumps, they have specialist for ASHP that are supposed to help with commissioning issues etc.  They hold the MCS certificate for most Grant installs.

 

Get your quote out and heat loss usage estimate, this is a design documents and if you are using more kWh than specified, Grant maybe the ones who have to fix it, even with the original installer going out of business.

 

Where is the controller installed? Inside or outside?

 

How do you operate the system, are you running weather compensation? What are your typical flow temp for central heating?

 

What is the thing with the blue lid?

[ProDave]

1 hour ago, JohnMo said:

Your cylinder thermostat photo 2 is set high, it is likely your heat pump will struggle to get up to that temperature and will keep trying using loads of energy. Turn down to high 40s.

It is unlikely the heat pump is actually using that.  They normally have a temperature probe in a pocket giving a much more accurate measure of tank temperature and allowing you to set the tank temperature from the control panel.

 

The traditional tank thermostat is just there as a required G3 safety device, to close the motorised valve and shut off the heat source in the event of a malfunction.  My own is there for just that eventuality and is set to 60 degrees.

 

To move this discussion forwards we really need historic gas usage, preferably from actual monthly meter readings not estimates, and the predicted heat loss calculations provided by the installer.

[ProDave]

2 hours ago, SteamyTea said:

but to be honest a gas bill of £200/month seems high

Not in todays high energy prices, especially if that is £200 per month for 6 months only, i.e. winter.

[SteamyTea]

4 minutes ago, ProDave said:

Not in todays high energy prices, especially if that is £200 per month for 6 months only, i.e. winter.

I must be getting out of touch, and living in a small, cheap to run house, in the warmest part of the country.

 

But if gas is around 7.5p/kWh, that is 2.7 MWh/month, or nearly 90 kWh/day.

To get that sort of usage, I would have to make my house ten times wider, to 40 metres.

[ReedRichards]

16 hours ago, Venkat Rangala said:

Then I got this idea (terribly bad) of getting heatpump and replace my gas boiler.

 

Not necessarily a bad decision.  At current fuel prices, a properly installed heating system using a heat pump should be marginally cheaper to run than a gas boiler (assuming you achieve an SCOP of 3).  And it's very green.  But if you thought your solar panels would generate enough electricity in winter to run the heat pump then you made a bad miscalculation.  And if you tried to install a heat pump as a drop-in replacement for a gas boiler and you did not change your radiators that most likely explains why the radiators no longer do their job.

 

 

 

  

[Drellingore]

EDIT - reading comprehension failure on my part

Edited February 16, 2023 by Drellingore

[ProDave]

21 minutes ago, ReedRichards said:

Not necessarily a bad decision.  At current fuel prices, a properly installed heating system using a heat pump should be marginally cheaper to run than a gas boiler (assuming you achieve an SCOP of 3).  And it's very green.  But if you thought your solar panels would generate enough electricity in winter to run the heat pump then you made a bad miscalculation.  And if you tried to install a heat pump as a drop-in replacement for a gas boiler and you did not change your radiators that most likely explains why the radiators no longer do their job.

Wise words.

 

At the moment, even with the higher prices, even with a perfect ASHP system in a good house, the savings over gas would be small, so the payback time would be huge.  If I had a working gas system I would not be changing at least not changing with the expectation of saving money.

 

I wonder what claims the supplier made (the supplier that has now gone bust so won't have to honour any claims)

[Conor]

51 minutes ago, ProDave said:

Wise words.

 

At the moment, even with the higher prices, even with a perfect ASHP system in a good house, the savings over gas would be small, so the payback time would be huge.  If I had a working gas system I would not be changing at least not changing with the expectation of saving money.

 

I wonder what claims the supplier made (the supplier that has now gone bust so won't have to honour any claims)

Only way it works out cheaper is when there is excess solar (rare) or, like us you run it on a cheap overnight tariff for a limited time. We're paying 10p per kWh, and with a SCOP of 3, means we're paying about 3.5p for every kWh output, less than half the cost of a gas boiler.

 

But that 7 hours is only enough when it's relatively mild, 7c or higher.

[Jimmyjazz]

What happened to your heat pump? It looks like it's been in a fight! Firstly what price are you paying for energy? If the system was put in by an MCS registered company they will have given you a handover document with all heat loss information and anticipated running costs. What temperature was the system designed to? Was the system ever commissioned properly and flow rates and flow temperatures set? 

I would get an installer involved who knows about heat pump systems to have a look over the system and set it up properly in the first instance as it sounds like it was finished in haste and not properly done.

 

[Sparrowhawk]

On 15/02/2023 at 19:33, SteamyTea said:

I must be getting out of touch, and living in a small, cheap to run house, in the warmest part of the country.

 

But if gas is around 7.5p/kWh, that is 2.7 MWh/month, or nearly 90 kWh/day.

To get that sort of usage, I would have to make my house ten times wider, to 40 metres.

They said bills of <£200/month so that could be combined heating and living. Our annual DD is (was) £200/month for gas & elec.

 

90kWh/day in an older house for heating only isn't unreasonable in cold spells. We have been over that for 8 days in February, and December/January had more days. Averaged over the year... yeah that would be high. We need more info.

[Radian]

On 15/02/2023 at 19:33, SteamyTea said:

But if gas is around 7.5p/kWh, that is 2.7 MWh/month, or nearly 90 kWh/day.

To get that sort of usage, I would have to make my house ten times wider, to 40 metres.

 

A 12m x 6m 4-bed detached house might have a total external interface area of 324m2. If 90kWh was needed to be input every day to maintain a 20oC indoor/outdoor delta, it would imply an average U-Value of 0.58W/(m²K) which would be consistent with something built to late 20th century building regs. But it's highly dependent on the airtightness and actual levels of insulation achieved.

[SteamyTea]

7 hours ago, Radian said:

imply an average U-Value of 0.58W/(m²K) which would be consistent with something built to late 20th century building regs.

Yes, not so far off what I worked out my place was before I did a few minor improvements.

I still think it is high.  Don't think my old Victorian place used that much, but I did move out of there in 2002, which means 21 years of my life seems to have vanished.