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How can I future-proof my heating and hot water?

Posted by Paul Hutchens on 17 June 2013 at 10:04 am

Q: I need to upgrade my heating and hot water system.  I am on mains gas and will move to an unvented system. I have looked at heat pumps but the size and location of my property does not seem to make this a sensible choice at the moment.  I even considered a thermodynamic solar panel system for heating hot water but from what I read this seems to be unproven for use in the UK and does not yet qualify for financial support.  My roof space is south facing and filled with solar pv so no space for a conventional solar based system. 

The sensible choice seems to be stick with a new efficient gas boiler. I will probably choose to divert my excess solar pv power through to the hot water cylinder via an immersion coil.  I will need to install a new hot water cylinder (horizontal orientation due to lack of space in the loft). I would like to try and future proof my choice of hot water cylinder in case new technologies develop in the years ahead.  What is the best way to do this? Or should I stick with a standard one coil cylinder as any new technologies that develop may well be able to be incorporated into existing cylinders? Am I missing something obvious or just trying to make things over complicated.

A: It appears that you have looked into this already and come to some reasonable conclusions. However, there are a few further things to consider.

Firstly, it sounds as though you have considered heat pumps – but did you just consider ground source which was rejected due to lack of garden area for the ground loop? If so you may want to consider an air source heat pump but ensure that you have a well-insulated property due to the lower temperatures produced and, as you are on mains gas, the payback may not be very quick.

So maybe an efficient ‘A’ rated gas boiler is the best bet. If there is no space for a solar thermal system, I cannot see this becoming a viable option in the near future. Also, if a heat pump is not going to be cost effective, there is no point installing an additional coil in a horizontal cylinder as this is more difficult and expensive (if it was a conventional upright cylinder it would not add much cost and would be worth doing “just in case”).

As for future technologies, it is difficult to predict! I don’t think you are making it too complicated – just thinking through rationally.

If you get a green deal assessment done, you may be able to claim cashback on a new efficient condensing boiler - Ed

How to use excess solar electricity for water heating

The benefits of using solar PV to power your immersion

Which is the best heat pump?

About the author: Paul Hutchens is founder and director of Eco2Solar, which installs solar systems around the UK.

If you have a question about anything in the above blog, please ask it in the comments section below.

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Comments

6 comments - read them below or add one

Si Temple

Si TempleComment left on: 4 March 2015 at 10:10 am

Like Paul, I am approaching the time to replace my 30 year old trianco gravity fed solid fuel boiler. I am however becoming overwhelmed with the amount of contradictory information given on the web. I have a 4 bed detached in North Yorkshire, well insulated, partial wet underfloor heating with the rest being traditional radiators, I have a 4kw solar power system which supplies the immersion with excess energy if required. We are NOT on the mains gas network.

Although incentives are attractive, I do not use that as my primary choice of system, I am looking for efficiency. Coal has remained one of the more stable prices over the last 30 years and a new g/f boiler would be in the region of £3k fitted. I have consisdered thermodynamic panals but as yet there is no definitive advice.

Any advice appreciated

Si

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Paul Hutchens

Paul Hutchens from Eco2SolarComment left on: 24 June 2013 at 9:06 am

Hi Nick

It is difficult to be definitive without understanding the (potentially complex) configuration that you have but thermal heat stores can be set up to take higher temperatures than hot water cylinders e.g. 70C +. This may help you be store more heat although ensure you have a blending valve on the hot water outlet to ensure that noone gets scalded.

It does not seem right that the heat is being dumped into the heating unless there is excess heat that cannot be used by the heat store so you should not have the LPG coming on any more than it normally would! You should be able to control this anyway - maybe with a timer?

I suggest that you contact your installer and ask for some advice.

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Nick Hanna

Nick HannaComment left on: 17 June 2013 at 12:48 pm

Hi Paul, interested to read that you might divert your solar PV to an immersion loop...we have a heat store linked into our solar thermal array (and woodburner), the store also has an immersion loop (as well as LPG gas loop). I just had an Immersun installed recently to divert the energy from our 2.6 kw PV array and I have been very impressed with its performance. According to the meter it has put 91 kwH into the immersion loop in 10 days. The only problem seems to be (and this is unrelated to your circumstances) is that the solar thermal and the PV/Immersun together put too much energy into the heat store which then 'dumps' the excess heat by putting it out through the central heating....so on a very hot day all the radiators come on! Not a problem in so far as our house is quite cold (even on sunny days), however the drawback is that if it does this at the end of the day then the LPG comes on to bring the water back up to temperature...which kind of defeats the purpose. However, I believe it does show that the Immersun is very, very effective.

All the best

Nick

 

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Plumb Solar LTD

Plumb Solar LTDComment left on: 17 June 2013 at 11:12 am

You can always add solar thermal on a west or east facing roof, on a flat roof or even on a vertical wall.

Also have you considered hybrid heat pumps using gas and air source together?

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Renewable Solutions UK Ltd

Renewable Solutions UK LtdComment left on: 17 June 2013 at 10:12 am

Biomass is also eligible for a £2,000 RHPP grant for domestic installations

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Renewable Solutions UK Ltd

Renewable Solutions UK LtdComment left on: 17 June 2013 at 10:10 am

As Paul says you should certainly consider an air-source heat pump, but if the levels of insulation are difficult to improve to the extent a heat pump is viable I'd certainly consider a biomass boiler. They will be eligible for the domestic RHI when it comes next Spring. They are also far more clean and easy to use than many people imagine. We have installed a great many domestic systems and whilst fuel cost is similar to mains gas now, it is not likely that they will rise at the inflation busting rate that gas does. 

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