Micro-CHP Boilers worth it?

akira181

The boiler in my flat is around 20 years old and pretty much on it's last legs. The circuit board just died on it and I picked up a refurb off eBay to get a little more life out it while I save the pennies for a replacement.

I'm struggling to find any recent reading material on micro-CHP boilers unless it's from CHP manufacturers, which I'm obviously taking with a pinch of salt.

So far, what I've read is that CHP boilers are just as efficient as combi boilers but generate electricity as well, making CHP better by lowering electricity bills. Allegedly even generate up to £100 a year if you're on the Feed In Tarriff scheme (I'm guessing that's if your boiler is on 24/7, even in summer).

The cons I gather are higher installation and servicing costs, considerably shorter warranties, and the government ending the feed in tariff.

The only con that's bothering me is the 2 year warranty vs a 10 year for a combi. Says to me that manufacturers are not completely confident in the durability of their own products.

Does anyone have any thoughts on CHP boilers or point me to some more reading material? Or should I stick to the tried and tested combi?

matelodave

I'd stick with the tried and tested. The CHP boilers had Sterling Engine generators and AFAIK weren't everso reliable although that might have improved.

I'm guessing that you can get some idea of the manufacturer's confidence if they only offer two years warranty instead of 7-10 for a conventional boiler

As you say the boiler has to be running to generate leccy and if the FIT has been knocked on the head then they really aren't going to save you much.

I think that they were clever idea but it didn't really take off - if it had, there would be lots and lots of info about them. You'd probably have problems getting them serviced and obtaining spares in the not too distant future as well.
I suspect that the average boiler engineer would be at a disadvantage unless he'd seen a few, so you'd probably have to get the manufacturer involved if there was a problem with the leccy side.

matelodave

matelodave wrote: »

I'd stick with the tried and tested. The CHP boilers had Sterling Engine generators and AFAIK weren't everso reliable although that might have improved.

I'm guessing that you can get some idea of the manufacturer's confidence if they only offer two years warranty instead of 7-10 for a conventional boiler

As you say the boiler has to be running to generate leccy and if the FIT has been knocked on the head then they really aren't going to save you much.

I think that they were clever idea but it didn't really take off - if it had, there would be lots and lots of info about them. You'd probably have problems getting them serviced and obtaining spares in the not too distant future as well.
I suspect that the average boiler engineer would be at a disadvantage unless he'd seen a few, so you'd probably have to get the manufacturer involved if there was a problem with the leccy side.

However have a shufti on the Green & Ethical forum to see if there are any users
or more info https://forums.moneysavingexpert.com/forumdisplay.php?s=&daysprune=&f=100

Chrishazle

Personally, I'm not convinced by combi compared to convertional condensing boiler with tank in loft. Daughter had/has combis in previous and current properties, would chase hubby out of shower by turning kitchen hot tap on - causing shower to go cold! That does not happen with our condensing boiler with hot tank in airing cupboard and cold water tank in loft, plus if CH system throws a wobbler (as it did a couple of weeks ago) we can still use the immersion heater for hot water.

akira181

Chrishazle wrote: »

Personally, I'm not convinced by combi compared to convertional condensing boiler with tank in loft. Daughter had/has combis in previous and current properties, would chase hubby out of shower by turning kitchen hot tap on - causing shower to go cold! That does not happen with our condensing boiler with hot tank in airing cupboard and cold water tank in loft, plus if CH system throws a wobbler (as it did a couple of weeks ago) we can still use the immersion heater for hot water.

The shower turning hot or cold when a tap is run is more to do with a combination of how the system is piped, bore size, and the system pressure. Usually means there's insufficient pressure on the hot or cold system to run multiple outlets depending what way it turns. My bathroom and kitchen supplies T-off just after the combi and has sufficient pressure to run the kitchen outlets without affecting the shower. Bathroom sink will affect the shower as that's on the same pipe run but that's fine.

A hot water cylinder will not help if your system is poorly piped or the shower is at the end of the run. However, most hot water cylinder systems generally have a dedicated branch for the shower / bathroom close to the cylinder for that reason.

The benefits of a combi as I understand is that it needs less space, less maintenance, hot water will not run out, and is more efficient as it's not constantly heating hot water when not required

After reading some CIBSE reports on CHP boilers, I think there's genuine potential for them to be the future as long as gas central heating remains commonplace. Especially the solid oxide fuel cell CHP boilers, which are not yet domestically available. Even if it doesn't provide all your electricity needs, it has the potential to considerably reduce your electricity bill and carbon footprint.

That said, it's still too new a technology, unproven reliability, and anything installed now risks being outdated and difficult to maintain due to development ramp up.

Sticking to the tried and tested combi is the best for my situation I think.