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Author Topic: Heat Pumps, Cooling and RHI Payments  (Read 2178 times)
vetinry
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« on: June 04, 2014, 03:11:44 PM »

Hello everyone
This is my first post here.  I've been trying to find an answer to a question on the internet but so far have drawn a blank.  There appears to be a huge amount of expertise here so I thought I'd join and see if anyone can help me.

Recently I was looking to install some air conditioning in the upstairs bedrooms in our house.  It's a sprawling bungalow with 3 upstairs room (2 bedrooms and a bathroom), which, because they are effectively directly under the roof, do tend to get a little bit warm in summer.

I was planning to go for a ducted split system to avoid losing too much valuable room space but was shocked to see how much the quotes were coming back (>4k).

Since the house is currently on oil, I started thinking about renewables and whether I could get a reversible heat pump, which could principally look after heating duties during the winter time, but with the capabilities to do cooling to just a couple of rooms in the summer.

Initially I considered ASHPs, but due to my concerns about maintained COP during cold winter months, I'm now thinking more about GSHPs.  From what I have been able to ascertain, I would need a borehole type installation to enable summer cooling (is this because close to surface soil temperatures get too high in summer months to achieve this?).

I can see a few of the models (Nibe etc) do appear to offer MCS approved products, which are capable of heating and cooling but I'm not sure whether I'm allowed to install one and then claim only for heating duties?

Does anyone have a definitive answer about this please?

Many thanks

Steve
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Ted
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« Reply #1 on: June 04, 2014, 03:53:25 PM »

Hi Steve and welcome to the Forum.

Check the domestic RHI Product Eligibility List downloadable from here https://www.ofgem.gov.uk/publications-and-updates/domestic-renewable-heat-incentive-product-eligibility-list to see if the model you intend buying is listed in the Commissioned On or After 09 April 14 section.
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Ivan
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« Reply #2 on: June 04, 2014, 04:08:30 PM »

One option is to use the Viessmann GSHPs which Navitron should be listing on their website shortly. The Viessmann is available with a 'passive cooling' option - from what I gather, it's not actively heat-pumping, but using the cool water in the ground loops to provide sufficient cooling to reduce house temperatures. It has the added benefit of helping to recharge the ground with heat ready for next season.

One thing to bear in mind when using your existing heat distribution system for cooling is that if you run it too cold, you'll get a lot of condensation which will then form damp areas - not desirable! Hence passive cooling is possibly a better alternative anyway
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vetinry
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« Reply #3 on: June 04, 2014, 08:35:21 PM »

HiTed and Ivan
Many thanks for your replies.

How effective would passive cooling be in a bedroom?

At the minute, I have a mixture of heat sources.  UFH in Kitchen, Thermaskirt in upstairs bedrooms, Myson Fan Convector in office, and traditional radiators in other rooms.  It's an ongoing renovation project and so I'm happy that if I need to either spec higher rads or get fan convectors in other rooms as I go to utilise better COP at lower flow temperatures, that should be ok.

The challenge I have is that the bedrooms can easily get into the high 20's in the summertime, and I'm not sure if passive cooling would be sufficient.

That's why I was still wondering about using ducted fan coils, which i can install in a small loft space above the 2 bedrooms, and which I could put on a seperate zone valve to control where the cool water was sent.  The current central heating pipes are pretty well insulated and I've already thought that I might need condensation trays / pipes for the fan coils if I went down this route.  I do like the added attraction of recycling the heat back into the ground though.

I can find some Nibe models on the list, but based on the model numbers, they look like "last year's" model.

I'll check out the Viessmann thanks

Next question.  Have those that have gone down the GSHP route been generally happy with performance? And would I be better going for turnkey approach or sourcing a drilling outfit (with experience in GSHP) and pump installation company seperately?

Any suggestions for Oxfordshire?

Many thanks

Steve
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mike7
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« Reply #4 on: June 05, 2014, 01:29:03 PM »

 A low-investment option you might consider would be to leave the oil CH as is and add one or two small split air-to-air heat pumps (aka aircon). One might be sufficient to sort your overheating, and with a second on the ground floor, they should carve a good slice off the bottom of your oil consumption curve. Some of the small units now have COPs in excess of 5 at 7C ambient, the sort of temperature you'll be getting a lot of over the heating season (and some of this summer) in Oxfordshire (I think this is in part due to their having relatively large heat exchangers for their capacity).

There's no RHI for these units but one reason given for that is that especially if you're off the gas grid, no further incentive is needed. Maybe you could invest the savings in improvement to the roof insulation?
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