domestic heating and hot water systems

Dipper · Post by **Dipper** » Thu Nov 21, 2013 4:34 pm

this is starting to suck the life out of me! i thought it would be an interesting project to spec the heating and HW system for the new hoose but its turning into a nightmare!

ive looked at ground source, air source, pellet boilers, stoves with a back boiler, solar HW, solar pv, thermal stores. Ive even looked at oil and various combinations of the above! ive talked to various suppliers, my architect, builder, mates and surfed till my eyes dried out. still no further forward!

complicating things is the new rhi scheme. if not for that i'd probably just stick in a stove, back boiler, thermal store and solar PV. could always stick in an oil boiler cheap if that lots not man enough.

anyone been through this recently? what did you go for and why? How are you getting on with your chosen system?

cheers

j2 lot · Post by **j2 lot** » Thu Nov 21, 2013 5:35 pm

We got a solar PV syatem a couple of years ago to get the highest payback tarriff (43p) before it was closed to new customers. System has been good and we are generating an average of about £90 per month and have probably dropped £20 a month on the leccy bill ( & got a refund on electricity of £250 at the end of year one)
Payback is still looking longer than originally quoted , getting closer to 10 years than quoted 7.
We also got smart controls on the boiler with a web portal for heating usage and PV generation and heating control through the internet and phone/ tablet control.
Overall very happy with the system but as much for its useability as its payback and the current tariff is much reduced (13p?) so the installation would need to be similarly reduced for it to make sense.

Edit to add - we have a combi bolier so no hot water tank therefore cant comment on Solar HW

David · Post by **David** » Thu Nov 21, 2013 6:13 pm

I too put a PV system in two years ago and it has worked faultlessly. Can be up and down on the figures but the average is what was promised. Also tried wood burner with a built in boiler - that was less successful as the boiler just caused condensate problems (you had to run it hot which was not always ideal)

I've just fitted a new condensing basic gas boiler this autumn and spent some money on upgrading windows and insulation. To be honest, keeping it simple and adding insulation seems to be the best value for money.

Dipper · Post by **Dipper** » Thu Nov 21, 2013 6:24 pm

cheers. feed in tarriff is low but systems are also now half the price. good to know they work.

gas is a no go as we're rural. insulation is to a pretty high spec. 125mm kingspan and 50mm wool(doubles as a service void for cabling). should be pretty air tight as well although not to passive house spec. no trickle vents and a hot air recovery system. UFH downstairs as well

wood burner is a given so figured we'd be as well getting the most out of it by adding a backboiler. what condensate issues were you having David?

David · Post by **David** » Thu Nov 21, 2013 6:45 pm

Dipper wrote: what condensate issues were you having David?

Well there were two problems, firstly the quality of the wood. If wood was at all green or damp, we found the moisture would condensate out on the back boiler and flue and it would work its way out and make a smelly pool on the hearth. To stop this we used to have to run it hard every few hours to dry/boil it off. In the end it caused a fire in the flue (blow torch out the top!) as the lacquer produced in this wet/dry cycle is also very flammable. It was quite a primitive and old Jotul design so maybe things have improved now.

Secondly, to help reduce the condensate problem we had to store the wood for about a year in a dry well ventilated place. Now that's quite a lot of space to lose. Basically it was too much hassle to save a few hundred quid a year (if that).

Edit to add: It is nice to have a fire in the living room, but just for pleasure rather than heating - we removed the boiler.

Scottish Scrutineer · Post by **Scottish Scrutineer** » Sat Nov 23, 2013 11:23 am

You do need to make sure the wood is dry for a stove. Seasoned at least a year and stored under cover, but ventilated. Also we only burn hardwoods to reduce the resins which coat the flue.

Sent from my iPad using Tapatalk
Renny

Al. · Post by **Al.** » Sun Nov 24, 2013 1:59 am

Dipper wrote:this is starting to suck the life out of me! i thought it would be an interesting project to spec the heating and HW system for the new hoose but its turning into a nightmare!

ive looked at ground source, air source, pellet boilers, stoves with a back boiler, solar HW, solar pv, thermal stores. Ive even looked at oil and various combinations of the above! ive talked to various suppliers, my architect, builder, mates and surfed till my eyes dried out. still no further forward!

complicating things is the new rhi scheme. if not for that i'd probably just stick in a stove, back boiler, thermal store and solar PV. could always stick in an oil boiler cheap if that lots not man enough.

anyone been through this recently? what did you go for and why? How are you getting on with your chosen system?

cheers

Oh dear, was disapointed to read this one!

Just about to start the process with a new build and in earlyish stages with the architect at the moment. Haven't even gone to Planning yet. Haven't had the time to review all the options although had discounted GSHP from a couple of people as we will have mains gas available. We don't want any wood burners as I am away about 7 months a year and the missus doesn'twant/need the hassle. We will just end up with 2 fires that are wall decoration more than anything. I want to be green but not at some ridiculous pay back period. We will be going for underfloor heating downstairs and radiators upstairs and high level insulation. We have allowed space for roof systems which ever they may be but need to get my head round them still. Haven't faced up to walking into the first showroom to be bombarded! I will watch your outcome with interest!

One thing I do want is to have the roof systems recessed in the slates as I personally hate the tacked on afterthought look of so many systems. I want it subtle and have a mate who has just done 2 newbuilds with them recessed and they look like Velux windows from a distance. Brilliant.

We fitted a Condensing (but not combi) boiler about 15 years ago and it has been brilliant on running costs in comparision to previous old system and we still have a hot water tank although used a presurised system - but not pumped - as we had some interesting pipe runs that gravity fed just wouldn't overcome. Present house is timber framed and was very well insulated by the standards of the day in late 70's but falling behind in comparison to what is top end now.

Keep posting on the outcomes!

Dipper · Post by **Dipper** » Sun Nov 24, 2013 12:01 pm

yours is a much easier decision. mains gas is still the cheapest option for your primary heating source. Its also reliable and a known quantity unlike gshp or ashp's which appear to have wildly varying success. The RHI scheme means your secondary source should pay for itself. solar panels for summer hot water would probably be enough. Pv panels would be an option as well but if you fit all led lighting your electricity bills will be quite low anyway

have fun!

kerryxeg · Post by **kerryxeg** » Sun Nov 24, 2013 12:16 pm

I've just finished a refurb of an old granite house, I had a similar debate and looked into all sorts of options. Max insulation was required to achieve the acceptable levels, so had to go for 140 mm king span all around. Windows and specifically glass was interesting, hardwood frames with k glass, which is double glazing with argon gas and a low emistivity coating.

I couldn't do ground source, but did look into a water well, this can still be done in the future. I did decide to go with UHF downstairs in a screed slab (pumped in wet, self levelling and doesn't crack). The screed has many advantages over concrete, it only needs to be 50 mm thick vs 80mm min for concrete which means it ill heat the slab much quicker. Upstairs I also went with a wet UHF system, this used a fibre board onto op the chipboard flooring with a 12 mm pipe running in channels within the 15 mm board. Then you can tile or put wood flooring directly on top. Ufh on a suspended floor is more difficult, but it does mean your whole system runs off the same supply and is easier to balance. Ufh does need some design attention to ensure that one room doesn't get all the flow - but it is pretty simple and I managed to do the work myself. The other consideration is control of the system, I went with poly pipe, their standard control with the programmable thermostats is excellent. Searching online you'll find almost everything at good discount. My UFh runs from an oil boiler, in the future, I could put in a water well and replace the boiler with a heat exchanger. For now it's working we'll and fuel use is down by about 1/3 due to the insulation, despite the how being a bit bigger.

I looked into a heat exchange air system, but concluded the running cost would reduce the efficiency offered. I only think this works is a fully sealed new build, which mine certainly isn't. I had a design done, and found I needed about 20 3" pipes running around the building to achieve the air exchanges required. So also ruled out on a too hard to install basis.

Something else to consider is fermicell. Nothing to do with efficiency, it's a cement fibre board you can use instead of plasterboard. Very heavy and tough, so ideal for bathrooms for tiling, or heavy wear areas. Also has a good fire rating for areas close to a fire.

Having been through the process I can associate with the range of options and indecision. In most cases I opted for the easier to install option. But you do have to make all these decisions early, make sure the spec is clear to the builder and stick to it. My builder was always keen to wriggle out of anything innovative, so my clear spec paid off.

Ferg · Post by **Ferg** » Sun Nov 24, 2013 3:32 pm

Al. wrote: We fitted a Condensing (but not combi) boiler about 15 years ago and it has been brilliant on running costs in comparision to previous old system and we still have a hot water tank although used a presurised system - but not pumped - as we had some interesting pipe runs that gravity fed just wouldn't overcome. Present house is timber framed and was very well insulated by the standards of the day in late 70's but falling behind in comparison to what is top end now.

We were looking at retro fit systems in the past year (previously electrical heating). Looked at everything including airsource, even ground source with a vertical shaft. In the end we found that the best solution for price vs efficiency vs requirements was the high pressure system boiler approach. Spoilt by having gas in the street compared to the chalenges of a rural situation though.

Scottish Elises