Hybrid Heat Pump Trial

spinaltap

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If you reside in the West Midlands, British Gas are looking for suitable customers to trial a Vaillant Hybrid Heat Pump in their home. It will be monitored over 2 years.

They will cover 70% of the installation cost - and you will be entitled to RHI payments too.

 
Having had a Heat pump system in a DIY hybrid configuration for about 5 years now .. No experimenting it just works. I got the house rebuilt in about 2007 and while I had requested a pellet burner, my builder convinced me otherwise. ..and put in an oil burner . So mixed radiators and underfloor and oil burner with mixing valve etc all in place. Eventually I got a Heat pump installed in parallel . There was some complex mixing blending valve put in by the installer to allow the oil burner come on under certain circumstances. Unfortunately the combination was not greatly successful. I then basically removed the blending valve and connected the oil burner in series with the heat pump with the flow going from the heat pump into the oil burner and then into house system and the return water going into the heat pump. That way any very hot water from the oil burner went directly into the house, and protected the heat pump. I added more insulation around the boiler .. except at its air intake.
Bottom line .It works a treat. My stats are that the heat pump has run for 17,000 hours .That is the compressor heating water ,and the oil burner for 92 hrs . So as you might imagine, the oil fills are very rare. The oil burner and boiler adds mass and thermal capacity to the heat pump system, so it has less frequent starts and stops .
The major trick with a heat pump is to try and reduce the average temperature that it needs to heat the water to, and this means reducing as far as possible all thermal barriers in the spaces you want heated. .. So all radiators full on, all floor heating full flow. .. Counter intuitive yes .
 
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British Gas surveyed my 1975 built home to determine its suitability for the trial.

If selected, all my radiators would have to be replaced with K3 (triple panel/convection) radiators. If not for their discount, this alone would cost the equivalent of replacing a condensing boiler.
 
British Gas surveyed my 1975 built home to determine its suitability for the trial.

If selected, all my radiators would have to be replaced with K3 (triple panel/convection) radiators. If not for their discount, this alone would cost the equivalent of replacing a condensing boiler.
Good luck, it sounds interesting, and you'll be getting everything at a discount, so a nice chance to upgrade.

Sadly,I don't live in the area and my house was built in the 1930s with solid walls, so I doubt I'll ever qualify for such a trial.
 
After my initial home survey, followed by a visit from the system designer, and then electrician, the installer team visited my home.

All my standard 15mm pipes would have to be replaced with a combination of 22mm and 28mm pipes. Micro-bore pipes are a complete no go (in our wet rooms). So, all the upstairs floorboards require lifting - and all box cowling between ground and first floor opened-up/enlarged to accommodate new pipe work (otherwise they would have to be surface mounted).

In addition to housing a new hot water cylinder in our airing cupboard, an additional 40 litre water buffer tank would have to be located close by. Our roof is shallow, so there’s no room there for the buffer tank. I suggested fitting a horizontal buffer tank instead, but they weren’t willing to do so.

This means that we are unable to take part in the trial. Like me, I doubt that many others will have the necessary space to accommodate all the necessary components required for installing an ASHP.
 
After my initial home survey, followed by a visit from the system designer, and then electrician, the installer team visited my home.

All my standard 15mm pipes would have to be replaced with a combination of 22mm and 28mm pipes. Micro-bore pipes are a complete no go (in our wet rooms). So, all the upstairs floorboards require lifting - and all box cowling between ground and first floor opened-up/enlarged to accommodate new pipe work (otherwise they would have to be surface mounted).

In addition to housing a new hot water cylinder in our airing cupboard, an additional 40 litre water buffer tank would have to be located close by. Our roof is shallow, so there’s no room there for the buffer tank. I suggested fitting a horizontal buffer tank instead, but they weren’t willing to do so.

This means that we are unable to take part in the trial. Like me, I doubt that many others will have the necessary space to accommodate all the necessary components required for installing an ASHP.
That went well then.
 
Having read the literature on Mitsubishi EcoDan Hybrid ASHP, and Daikin Hybrid ASHP, neither company require home owners to replace their existing pipework nor radiators.

With the EcoDan Hybrid ASHP, Combi Boiler owners don’t require a hot water cylinder, either.

If you opt for the stand-alone Daikin High Temperature ASHP, with water flow rates of 70 degrees, you don’t need to replace your existing pipework nor radiators. In this situation, their Hydrobox, plus hot water cylinder are the requisite additional components.
 
Just had the install by British Gas done at mine. 1960s some, 225m2. Guys did a really good job. You need about 2m of free wall space in 1 location, or an open mind / creativity to house it around the home. Discount is massive (70%)
 
Do you have external wall insulation?
Did they give you an idea of the savings?
What happens after 2 years?
No, not yet. It's a 60s build which had cavity wall insulation blown in the 80s.

No, nothing on savings or costs other than it could cost slightly more in elec than equiv of gas. I have solar panels so hoping to offset that difference and be the same as gas or cheaper. CoP is well over 4 at the moment....but it is nice out!

Nothing happens after 2 years.
 
You can see my comments - I can't honestly pass judgement until i have had a cold spell. Some of what he says is correct, some of what he says is wrong....
 
An interesting and entertaining interview about the future of heat pumps and renewables in the UK:
 
In discussion with a member of British Gas’ Hybrid ASHP team; the Boiler that is installed as part of their Hybrid ASHP package is restricted to 45 degrees (temperature), to match the flow rate temperature of the ASHP.

Therefore, any notion that the Boiler would provide for hotter radiators during extreme cold weather is unfounded.
 
Interesting videos. I think air source heat pumps aren't the right way to go.
Any views on ground source heating?
 
British Gas surveyed my 1975 built home to determine its suitability for the trial.

If selected, all my radiators would have to be replaced with K3 (triple panel/convection) radiators. If not for their discount, this alone would cost the equivalent of replacing a condensing boiler.
Why would that be needed? If the system heat the water to the correct temperature then the size of rad. Should be as normal or did the system they suggest no do this?
 


Interesting video. I wondered how these air source heat pumps could work with lower air temperatures. Looks like they don't work that well, and need supplementary heating measures. Plus there's a lot of additional installation needed to upsize rads. And this is assuming your house is adequately insulated.
 
Having had a Heat pump system in a DIY hybrid configuration for about 5 years now .. No experimenting it just works. I got the house rebuilt in about 2007 and while I had requested a pellet burner, my builder convinced me otherwise. ..and put in an oil burner . So mixed radiators and underfloor and oil burner with mixing valve etc all in place. Eventually I got a Heat pump installed in parallel . There was some complex mixing blending valve put in by the installer to allow the oil burner come on under certain circumstances. Unfortunately the combination was not greatly successful. I then basically removed the blending valve and connected the oil burner in series with the heat pump with the flow going from the heat pump into the oil burner and then into house system and the return water going into the heat pump. That way any very hot water from the oil burner went directly into the house, and protected the heat pump. I added more insulation around the boiler .. except at its air intake.
Bottom line .It works a treat. My stats are that the heat pump has run for 17,000 hours .That is the compressor heating water ,and the oil burner for 92 hrs . So as you might imagine, the oil fills are very rare. The oil burner and boiler adds mass and thermal capacity to the heat pump system, so it has less frequent starts and stops .
The major trick with a heat pump is to try and reduce the average temperature that it needs to heat the water to, and this means reducing as far as possible all thermal barriers in the spaces you want heated. .. So all radiators full on, all floor heating full flow. .. Counter intuitive yes .

What are your running costs? Relative to your previous setup. Is it more or less expensive to run?
 
The Government’s report of 2016, assumed that most older housing stock required high temperature ASHP’s - so that existing Radiators and pipework would not have to be changed.

The issue with low-temperature ASHP’s - especially in a hybrid system - is the requirement for a 40 Litre Buffer Tank, in addition to your existing hot water cylinder.

The further complication is that while low-temperature ASHP’s have an energy efficient COP of around 4.5, a high-temperature ASHP is more likely to have a COP of only 2.1. Unless you’re upgrading your central heating from expensive oil, a high-temperature ASHP (if you’re changing from Gas) is going to be very expensive to run.

All is not lost, though. RED ASHP, designed in Northern Ireland is an ultra high efficient, high temperature, ASHP. It produces the kind of high energy efficient COP that a low-temperature ASHP produces. Also, it does NOT require the installation of an additional Buffer Tank.

 

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