Suggestions for future heating system

[robotmannick]

Hi all,

I was hoping to canvas your opinions on what kind of heating system I should install in my house.

I currently have a 40kW biomass boiler which provides all heating and hot water for a 6-bedroom 220m2 house. Happy to elaborate on the biomass boiler if anyone is interested, but the short version was that it made financial sense whilst I was receiving the RHI, but came at the cost of a lot of work and not insignificant inconvenience in terms of forward planning of when to light it etc. Now that the RHI payments have finished, I'm wondering what system would be best for the future. Thoughts so far:

1) Keep the biomass boiler. No installation cost, but the cost of logs, combined with the physical work (and time) required to manage log stores and feed the boiler, not to mention the inconvenience makes this somewhat unappealing.
2) Replace with an oil boiler. Seems like a backwards step - that's what I removed when I installed the biomass boiler. I have an oil tank which I believe to be sound - there is still 100-200 litres of oil in the tank, but given that it's been there for 8ish years, can (should?) I use it with a new boiler? If not, I'll have to arrange for draining of the tank and disposal of the oil. If I'm doing that, maybe I should also replace the tank too as I have no idea what contaminants have collected in there over the years. Probably the cheapest option in terms of installation, albeit not the cheapest to run and and not very green.
3) Replace with an LPG boiler. I'm not overly keen with having a large LPG tank in the garden - I know it's perfectly safe, but I saw a video at work of a BLEV explosion and is scared the bejesus out of me. However, also a relatively cheap option to install, but similarly not very eco-friendly, nor the cheapest to run.
4) Solar thermal. I don't have much South-facing roof space and even if I did, I'd need a pretty large (expensive) collector to heat the whole house. Cheap to run and good eco-credentials though.
5) Air source heat pump. I reckon on spending maybe £15k on this option plus BoJo's £5k grant. I don't have underfloor heating though, so would be reliant on existing radiators. Retrofitting underfloor heating isn't unfeasible as I am renovating parts of the house, but I can see the costs spiralling.
6) Ground source heat pump. I have a garden about the size of a tennis court so could potentially dig trenches for the pipework. Access is limited to about a 1.5m width, so boreholes would require removing a hedge in the back garden and reinstating (not averse to this as there's a prickly one that I'd like to get shot of anyway). I'd guess we're talking £30-£40k though for this option. Maybe the cheapest and greenest option in terms of running cost?

Of course, there may be a combination solution...I have a 3000 litre thermal buffer as part of the current installation. For instance, I can add solar thermal to feed into this which would probably do me during the summer months, then keep the biomass boiler for topping up during the winter.

So then learned folks: what are your thoughts? What would you do and why?

 

[Jameshow]

Insulation insulation insulation.

Whatever you do put insulation top of the list.

Ashp gshp esp.

How about a log burner with back boiler?

Not an expert by any means.

Cheers James

 

[Fitzroy]

Insulate first, with a contractor who knows what they are doing, the devil is in the details.

Non fossil fuel solution as IMHO the cost of these will only go one way over the next 20years, either due to supplydemand or legislation and green tax.

Ground source heat pump is the gold standard and long term boreholes etc are value add to your property but my understanding is you want underfloor heat rather than rads. Air source heat pump is a poor compromise, all the same need for ufch but just a cheaper install cost for a less efficient system.

It is such a tough decision though, a long term investment for the greater good that you may never get the return from or a short term lower install cost that is easier to financially stomach but may feel wrong.

 

[Just4Fun]

We have generally been happy with our GSHP installation despite some reliability issues, apparently now sorted. Maybe our experience can provide one or lessons.

The advice to insulate first definitely makes sense. When we got ours in about 2007 we were getting quotes of 30 000 euro and up, which was beyond our budget. Then we discussed it with a plumber who was here for something else and he took a very different view to everyone else. Other people had sized the system based on the size of the house, which is large. This guy looked at the amount of oil we had been burning and calculated the required heat pump size to produce the same output. Based on this he quoted 13 000 euro and we went for that. It seems our house was already well insulated and this cut down the initial installation cost as well as the running cost.

The oft-seen advice to change to under-floor heating, or fit more and/or larger radiators, may or may not be good. The key is the temperature of the water circulating in the system. We already had a lot of rads and the system ran at a maximum of around 55C, even in the coldest winter. This is (just) within the capability of a GSHP so we didn't need to improve the rads, we just added the GSHP to the system.

The choice of horizontal pipe (straight or slinky) or bore hole depends on the site. You need advice from someone knowledgable. Our system uses horizontal pipes but that is what suits us here and may not be the best where you are.

The heating system runs well, and needs no attention on a day-to-day basis. I like that a lot.

Oh, I should mention that I cannot comment on GSHP for hot water. Our GSHP does heating only. That was a design decision when we put the system in. In retrospect it may have been the wrong decision but, for various reasons, it seemed correct at the time.

 

[Terry - Somerset]

There are several different needs - I am not convinced one approach meets all needs.

Irrespective of the solution adopted, insulation must be top of the list.

For space heating I would look at combined aircon/heating split units. These are reallly just ASHP without the hot water capability. It is possible to have a single outdoor unit serving several wall mounted indoor units. You get the benefit of cooling in summer if desired.

Like GSHP and ASHP they need a power supply - given your house orientation this could be PV, PV + battery, or mains. A larger system could provide some lighting,cooking(?), appliances.

Hot water could be electric (PV or mains), evacuated tubes or panels, gas cyinder or small ASHP.

This all gets a bit complex - much depends on the balance you decide between investment vs future running costs. The only high probability is that oil and gas are likely to increase in price.

 

[D_W]

I have a split on the add-on part of my house. It's efficient until the temperature gets well below freezing, but I don't think that'll be much of a problem in the UK.

At freezing or slightly below and anything above, it's a marvel. The only question is whether or not HVAC installers are going to try to rob you selling you one. The local installer here wanted $5500 to install a unit that I found (mitsubishi) for $2200. This would normally be what you'd expect with labor intensive installs, but if you have a typical unit right outside of the living space, there's little to the install and even with mounting the exchange heads on a masonry wall, it only takes an experienced installer a couple of hours.

Since I had a contractor doing the addition, I wasn't allowed to just do my own, and I used his installer ($750) and bought the unit through plumbing supply rather than the territorial (and arrogant and very entitled) factory authorized installer that's in my area.

7 years so far, no issues and no maintenance. AT the cost of the units, I'll just buy something else to put in its place when it quits.

 

[dickm]

Have a slightly similar dilemma; our house is highly insulated (came on a lorry from Sweden) with forced air ventilation and heat recovery. Four bedrooms, big lounge, big kitchen and (heated!!) workshop need about 6kW when it's below freezing. We have a small oil boiler which runs for a couple of hours a day, plus a woodburning stove. So what's the problem? Mainly my age and increasing problems with cancers. The oil boiler will probably see me out, but on its own may struggle a bit, and cutting/splitting logs is getting difficult both from availability and my capability.
Air source heat pumps strike me as a total con until all electricity is from non-carbon sources. Ground source should be better, but still not all they are cracked up to be.
Maybe I should not have sold that pellet boiler to a member of the forum!!

 

[redhunter350]

Hi I assume Berkeley Gloucestershire ? I am not an expert by any means however my sisters house in Cambridgeshire has ASHP heating and hot water, works very well and was installed about 3/4 years ago. They were in the position of a complete renovation of a 5 bed very well built house.

As has been said insulation is clearly of the utmost importance and although the house was well insulated they had this upgraded even more, in my humble opinion underfloor heating is also essential because it works well at lower water temperatures -- I may be wrong but thats my feeling.

 

[eribaMotters]

This has got me thinking. In the next year or two we will be moving and knowing my luck another full refurb will be needed.
Heat pumps are expensive to install and run. Heat recovery systems are high tech set-ups. I want something that is reliable, low tech and will not need an expensive engineer to maintain and fix when it will go wrong.
Past experience and an earlier comment confirm insulation is the key. We have a 120m2 bungalow at present and total energy costs are £85 a month for gas and electricity.
If starting from scratch now I would be thinking electric is the way forward. I'd wire up electric radiators, all on one common timed circuit with individual thermostats. From past experience an emersion heater in a large well insulated tank will cope with the demands of a family so no problem with just the two of us and occasional guests.
The cost of electricity is going to be lower than gas and you can produce the stuff yourself. it is or should be greener than gas. The wiring is a dam site easier to do than plumbing, I'd just have to get it signed off.
I'm probably living in cuckoo land, but this would be my starting point from which to learn and develop.

Colin

 

[Ozi]

It's a question I think a lot of us are asking right now. I'm thinking that the answer for me at least is probably more than one heat source. We have solar hot water from vacuum tubes on the roof, installed 13 years ago, first service this year and no issues. I have been very pleased with these they give lots of hot water through the summer, five people all get showers plus the washing up etc. meaning my gas boiler only runs when central heating is needed. I have insulated as much as I can, my house doesn't have good cavity walls and lots of iron in the blocks it's built from. This is going to sound daft but I bought my wife a heat pad for her chair, she likes the place much hotter than the rest of us and it takes about a month off each end of the central heating season. I'm thinking of getting a small log burner as we live out in the sticks I don't think it will cause air quality issues and I get a small amount of free fire wood. In your position I would keep the system you have but try all means to minimize it's use, insulation as mentioned by all but also I think most of us are of an age to remember the woolly jumper, we used to live in houses with much less insulation and although my parents had central heating it only run when to not run it would have meant frozen pipes, I'm as guilty as anyone of heating my house to T shirt temperatures all year round then feeling bloody freezing outside when it gets down to 10°, it's time to stop doing that unless you have people who are vulnerable to consider.

When I get off this soap box it's going on the fire!

 

[Spectric]

log burner

Yes a good source of heat but not so good if you also try and use one to provide hotwater by getting on with a heat exchanger. A company up here has been over whelmed with orders for them since this gas hike and now has plenty of work.

 

[mikej460]

We had a top quality log boiler and solar hot water system feeding a thermal store and it was a nightmare to maintain. Most of the problems were down to our inability to source good quality and dry logs, especially after Christmas as the log suppliers started to run out of seasoned logs, so we ended up with load after load of damp sycamore. The solar system was good in winter but boiled in summer, partly due to an undersized thermal store. The boiler itself needed regular checking and attention which wasn't possible whilst holding down a demanding job so we sold the entire system and installed a wood pellet boiler with a Heatrae Sadia Megaflow hot water tank and it is so much better.

 

[Fitzroy]

Heat pumps are just a refrigeration cycle, so no more complicated than that. Reliability will improve as more are installed. The integrity of the internal parts wouldn’t worry me. The integrity of the external elements will depend on the competence of the installer. If installation numbers increase rapidly, it’ll pull the cowboys in and there will be plenty of horror stories.

 

[Woopecker]

Hi all,

I was hoping to canvas your opinions on what kind of heating system I should install in my house.

I currently have a 40kW biomass boiler which provides all heating and hot water for a 6-bedroom 220m2 house. Happy to elaborate on the biomass boiler if anyone is interested, but the short version was that it made financial sense whilst I was receiving the RHI, but came at the cost of a lot of work and not insignificant inconvenience in terms of forward planning of when to light it etc. Now that the RHI payments have finished, I'm wondering what system would be best for the future. Thoughts so far:

1) Keep the biomass boiler. No installation cost, but the cost of logs, combined with the physical work (and time) required to manage log stores and feed the boiler, not to mention the inconvenience makes this somewhat unappealing.
2) Replace with an oil boiler. Seems like a backwards step - that's what I removed when I installed the biomass boiler. I have an oil tank which I believe to be sound - there is still 100-200 litres of oil in the tank, but given that it's been there for 8ish years, can (should?) I use it with a new boiler? If not, I'll have to arrange for draining of the tank and disposal of the oil. If I'm doing that, maybe I should also replace the tank too as I have no idea what contaminants have collected in there over the years. Probably the cheapest option in terms of installation, albeit not the cheapest to run and and not very green.
3) Replace with an LPG boiler. I'm not overly keen with having a large LPG tank in the garden - I know it's perfectly safe, but I saw a video at work of a BLEV explosion and is scared the bejesus out of me. However, also a relatively cheap option to install, but similarly not very eco-friendly, nor the cheapest to run.
4) Solar thermal. I don't have much South-facing roof space and even if I did, I'd need a pretty large (expensive) collector to heat the whole house. Cheap to run and good eco-credentials though.
5) Air source heat pump. I reckon on spending maybe £15k on this option plus BoJo's £5k grant. I don't have underfloor heating though, so would be reliant on existing radiators. Retrofitting underfloor heating isn't unfeasible as I am renovating parts of the house, but I can see the costs spiralling.
6) Ground source heat pump. I have a garden about the size of a tennis court so could potentially dig trenches for the pipework. Access is limited to about a 1.5m width, so boreholes would require removing a hedge in the back garden and reinstating (not averse to this as there's a prickly one that I'd like to get shot of anyway). I'd guess we're talking £30-£40k though for this option. Maybe the cheapest and greenest option in terms of running cost?

Of course, there may be a combination solution...I have a 3000 litre thermal buffer as part of the current installation. For instance, I can add solar thermal to feed into this which would probably do me during the summer months, then keep the biomass boiler for topping up during the winter.

So then learned folks: what are your thoughts? What would you do and why?

Given current financial climate I would keep the biomass boiler but change to wood pellets future fuel prices are set to go one way and it’s not in our favour, the other question would be if you already have a biomass boiler and received RHI would you qualify to have that removed in favour of another system , Ref your oil tank at 8 yrs your oil is now contaminated and will hold water from condensation in the tank, you may also require new tank if not to standards ( double skin)

 

[Jones]

Spend money on insulation first, then look at ventilation, we have a mvhr system that gives good draught free ventilation and removes moisture to give a comfortable house. When draughts are reduced and air is dryer the comfort temperature is lower.
I don't know much about heating systems we went for oil and burn about 500L a year for large detached heating and dhw which with boiler cost has worked out cheaper than biomass over the years. We also have a borehole water supply it cost £5000 10 years ago 70 m deep ,through rock all the way it took 8 hours to drill. That rig was on a Bedford 4 tonner I think smaller rigs will drill slower but £50000 seems a bit much.

 

[Jacob]

Future is uncertain so lowest tech and least dependent on infrastructure and the outside world, makes sense?
Insulation x 3!
Woodburner for direct heat - we burn all workshop waste, sawdust, cardboard etc as well as stuff we bring in.
Solar water with largest possible thermal store. Can this be self sufficient without mains electricity?
I'm retreating into survivalist mode!
I foresee massive expansion of air/ground heat-pump usage to be followed by massive maintenance problem with massive shortage of engineers.

 

[Krome10]

This is going to sound daft but I bought my wife a heat pad for her chair, she likes the place much hotter than the rest of us and it takes about a month off each end of the central heating season.

I'm not laughing. But I am smiling People tend to put insulation at the top of the list, which I agree with, but I think joint top are the simple measures such as a jumper etc, etc.

I have thermal long johns and tops, thick socks etc which I wear throughout winter. The house is usually around 16-17c in winter at peak. When it r occasionally reaches 18-20c we start to get hot under the collar and unconformable, even without the thermal layers. Most people naturally acclimatise to their environment; be it levels of heat, hunger, etc. Heat a house well into the 20s, and over the years you'll feel the cold a lot more as your body resets to the new "normal". I totally accept that different people have different tolerances, but at the same time I think the above holds true.

I personally can't understand why how we use energy is often not discussed, or at least left to the margins. So many people have a shower a day (some more!), wash clothes after one or two uses, heat houses to the point they can sit in shorts and t shirts, etc etc. If we hadn't evolved into this era of cleanliness, I think a lot of what is now considered normal would be considered anal OCD type behaviour. We scramble around looking for new innovative ways to make everything greener - which is a great thing - but for me the elephant in the room is our usage.

I feel I must say something on topic now to counter my off topic rant! To the OP, I would be inclined to stick with what you've got for the time being. I think we're in a period of flux and it's hard to know what the future will hold for different energy prices, changing installation prices and grants, new green legislation, and new innovation in heating systems which perhaps haven't surfaced yet.

 

[nickds1]

We did an eco build 16 years ago and the GSHP supplying all heating and hot water was part of that. We buy our electricity from an 100% renewable supplier.

The house is two parts - an old oast that was gutted and completely rebuilt and a new part that looks old, but internally is block and beam.

The new part is UFH with the b&b slab acting as thermal store. The old bit has standard emitters which are sized for the lower GSHP water temperature.

Regardless of your eventual heat source, you need to insulate to the very highest standard you can. Just do it.

We hate the whole passive House thing, so we do open windows and doors etc - insane to live in the country and then live in a sealed box!

As we did the GSHP at the same time as the build, it was pretty cheap to install as we had diggers etc. on site - most of the exterior install was done in a day, though it took the lawn two years to recover.

In the 16 years the system has been in, it's given no problems and not missed a beat. Just love it!

Regarding reliability, this is NOT new technology. Heat pumps have been used in Scandinavia and Europe for many decades and the technology is simple and well established. We were in the first 100 domestic installs in the UK, but the system we used was an IVT Green line - IVT are now owned by Bosch, but are an established Swedish company with 10s of 1000s of installations.

The technology is straightforward and not complex - basically a fridge in reverse. It's mostly circulation pumps, filters and motorised valves, all of which are standard parts (Grunfoss etc.) - the only bit that is specific to an HP is the heat exchanger and that's not rocket science either - much the same as a fridge compressor.

It's an extremely mature and well understood technology. The UK is just a bit late to the party - the rest of Europe and North America etc. have been using this stuff for many years.

 

[Krome10]

I'm retreating into survivalist mode!

I foresee massive expansion of air/ground heat-pump usage to be followed by massive maintenance problem with massive shortage of engineers.

I agree with both those points.

Regarding the second point, we explored gshp option when we moved into our current house. Would have required possibly X2 100m boreholes and the proposed site was right next to the house. We live in a very wet area with a high water table, and when I thought about it I didn't like the freeze-thaw aspect of the ground on which my house sits; half of which doesn't have foundations. I'm no builder so perhaps that's unfair and unfounded, but I do seem to remember finding some stuff on the internet along similar lines.

 

[Jacob]

Survival mode again - yes as much insulation as you can but also internally zonal so that your main living quarters, the woodburner, the thermal store, are all in one zone, with the rest of the premises cooling down if things are getting difficult.