Central Heating upgrade

[James Warlow]

Hi Guys - I hope you can help as I'm in bit of a quandary!

I live in a well insulated bungalow in Norfolk. We have solar PV 3.92kW array, Solar Thermal, a Clearview 650 12kW wood burner with back boiler and a Gledhill Multifuel Solar Thermal store 525lt which has 3kW immersion heater - we have 5 rads and a bathroom towel rail with all heat coming from thermal store. All installed in 2012 prior to our ownership. I have fitted electric underfloor heating in our hallway as a core warmth. We do not have Economy 7 (or whatever it is called now). My electric bill last year was £853 and through Fit's and RHi I got back £1054. We have an EPC of B+

Here's my problem.
Whilst we never have any issues with hot water for 2 showers etc provided in summer and good days like last weekend by the solar panels, and during winter months by the wood burner (only normally used for around 3 hours in the evening) I have an issue with the heating system. Currently if, on a really cold day I want to run the rads (I work from home in architecture lol) from the moment I turn the hall stat up the rads are hot within a few minutes but this only lasts for around 10 mins before cooling off as obviously all the stored hot water is being used up! This isn't sufficient to heat any rooms to any degree but also means I then need to use immersion heater in 1 hour boost to get hot water up to temp again for showers etc. To compensate we tend to trundle a couple of Delonghi electric oil rads around yet still manage low bills.

My question is I've been looking at loads of options such as new ASHP (even with gov grant this will still be £9k and told involves a lot of disruption with removal of all old rads etc and so on. We do not have gas apart from LPG for cooking hob and I don't want oil as nowhere for boiler inside, no where to hide a tank and I don't like the ever present smell of heating oil!

I've been told to firstly to fit an inverter to use the electric from the PV panels that is wasted?also replace my existing TS with a modern more efficient model (I've no idea which). The next thing is to install an electric boiler to run purely the heating somehow linked through TS to ensure should tank ever get too hot from the powerful wood burner excess can be run off by turning rads on (there are 2 heat sink rads off back boiler already). The idea is that the solar PV could run the electric boiler when needed and other appliances when not. A boiler we've looked at is one by Thermosphere - 6kW 27amp or 9kW 40amp.

Does this seem to make sense or can anyone suggest a better method as I had set a budget of around £5k. My other thought is that if we ever came to sell we don't actually currently have a real form of central heating - yes underfloor would be fab but I've fitted new laminate floors throughout and skirtings!

Would really appreciate some help so I don't make the wrong decision...............sorry for long message

 

[vxxbcks]

Can you get RHI for an ASHP in addition to claiming for whatever is left on the existing system?

 

[James Warlow]

You can but an ASHP is still £9k after the £5k grant as you have to have both hot water and heating to get grant. You can still get RHI.

 

[vxxbcks]

RHI pays for ASHP based on consumption per EPC and the HP SCOP on the design flow temp. It's not limited to £5k (in England, anyway).

 

[oldbutnotdead]

You've already got an electric boiler that can feed (well boost anyway) the heating system, its called the immersion heater. Your solar PV panels will already have an inverter on them (you get FIT payments), you need one of those toys that diverts every unused amp from the panels into the immersion heater.
If you can get more insulation round the thermal store then do it. If you don't have a loading valve on the wood burner, fit one- along with other benefits it prevents hot from the store back-circulating through cold woodburner.
Consider an LPG boiler (not sure about costs for the big tanks that make LPG cost effective, price per kwh on portable cylinders is similar to electricity.

 

[James Warlow]

Thanks for reply. The tank does have a lot of extra insulation already and no more space to add more. Yes I know there's the immersion heater but where it sits I don't think it makes sense as that wouldn't cope with rads running for say 30 mins which is why looking at electric boiler. Yes sorry I don't know the name of the diverter for solar but the inverter is a Sunny Boy and intension is to use every little drop of unused electric to run the boiler.
Yes we do have a thermostatic valve linked to a stat that opens gravity feed from wood burner to the thermal store so as soon as wood burner what drops below that the valve shuts to stop feed back and loss.
We use LPG to cook on the hob but I don't have the space in kitchen (which was only fitted a year ago at £15k) to fit a boiler neatly and no space in thermal store cupboard to fit one and get a flue up to outside - tanks cost a lot to install and look ugly as well - sorry. Hope you can see what I'm thinking....................I do have a specialist visiting next week who does all forms of energy efficient heating systems and he even wonders about a small ASHP to purely do the 5 rads using excess electricity from the PV with a diverter valve to allow excees in TS to be used in rads to prevent any overheating if my son decides to really get the clearview going (log munching).

 

[Terrywookfit]

If you have space for a ASHP, You have space for an external oil fired boiler.

 

[James Warlow]

Yes but I don't want oil - it stinks!!!! Also additional cost on top with no savings using the PV

 

[oldbutnotdead]

Solid fuel flow control valves etc. get pricey cos they have to be engineered to fail safe- fallover valves etc are a complication best avoided. Q for your expert- can an ASHP successfully feed into a thermal store (i suspect they run at too low a temperature but worth a go).
Your TS combined with solar in theory gives the best performance, allows you to bank energy from the daytime and release it in the evening. Store sounds big enough (bigger is better up to a point), beware of 'more efficient modern ts', its all basic physics so may well be snake oil involved (much like certain electric heating systems with some very misleading consumption figures).
Maybe look at caravan/small boat lpg water heaters (prob not worth the investment if you're on bottles).
Talking of bottles, have a look at these https://www.ebay.co.uk/itm/Refillab...VEweuf4yAURPPCdb1cQGVevzPCLRvkhYaAtM1EALw_wcB , chunky investment now (they were £120 last year,) but cost/kwh much lower

 

[vxxbcks]

I'm not familar with wood systems but it sounds to me that it's simply not being used enough and not providing enough output. Could you just replace the wood stove with an ASHP and then install a log burner maybe.

 

[James Warlow]

It is a log burner with 12kW made by clearview. It's actually very powerful. The existing TS cannot store enough water to run rads - that's the problem. The guy is thinking of ASHP just running rads

 

[Bodgedbuild]

Don't know if it would make any difference but, you do NOT have to replace your rads with many of the latest heat pumps. I got an 80 degrees C ASHP and I have found it able to get my rads way hotter than I require, with that in mind when my mother-in-law decided to go with an ASHP I told her not to bother getting a high temperature one. Many of the R290 (refrigerant) Heat pumps will heat water in the 70 degrees centigrade range and if you stick with big brands like Hitachi/Panasonic etc you won't notice much change in water temperature even at extreme low outdoor temperatures.

 

[muggles]

It sounds to me like your primary heat source is your Clearview and you're just not running it enough. Assuming the system has been correctly designed, it'll keep your entire house warm via the thermal store provided you actually light it. If you only run it for a couple of hours in the evening, it's not all that surprising that you have no heating through the day.

I can't see an ASHP being compatible with what you have, at least not without being hideously expensive to run, and your £5k budget isn't going to cover the conversion cost.

If you want more electric backup, how about upgrading the immersion heater to a 6kW?

 

[vxxbcks]

It is a log burner with 12kW made by clearview. It's actually very powerful. The existing TS cannot store enough water to run rads - that's the problem. The guy is thinking of ASHP just running rads

Yes, the stove needs to be lit. 12kW must be enough for 7 radiators unless they are gigantic. But cooling a 500l thermal store from say 80 to 40C releases only 24kWhr which clearly is only enough to provide 1kW for 24 hours, which is unlikely to be enough to adequately heat the house.

 

[James Warlow]

Thanks for the replies. Firstly we inherited all of this from previous owner who had intended to stay here but due to his wife being made redundant (a solicitor made redundant!) he moved before completing whatever else he was doing so we are stuck with what we have. I understand running the Clearview all day would adequately provide enough water for the rads but the amount of wood needed (at cost of £140 a half load) would soon add up. I've just about used up my double load delivered in October and that's using the burner most, but not all evenings (normally as said for around 3 - 4 hours) with occasional weekend days for around 6. So if I ran it most days for say 6 hrs or so I'd need 3 double loads of wood so cost being in region of £360 for wood. This would be fine but the living room would be ridiculously warm and I'm not looking for heating to run all day long and plus the fact working means I'm not going to want to be constantly having to stoke the fire. I'd like to walk in hall and turn stat up and walk back into office knowing rads will heat up and switch off when needed without any further intervention. SO yes a good idea but not suitable for my needs. I've been told by Gledhill that unfortunately a 6kW immersion won't fit/work in this TS sadly as that was one thing we were looking at as this could be run by the excess solar PV hence looking at a ThermoSphere electric boiler to purely run rads.