Newbie Question - Microbore CH and Thermal Store

[tarrel]

Hello,

We currently have an oil-fired combi-boiler feeding a pressurised central heating system with 9 rads, connected with microbore tubing.

I'm planning to have this converted to a renewable energy system and, from all the research I have done so far, I am looking at the following:
- Wood burning stove with back boiler (or maybe solid fuel Rayburn), feeding a vented thermal store, with CH fed directly from the store
- Retain the oil boiler as a back-up, heating the thermal store via a coil
- Solar thermal providing heat to the store via a coil.
- DHW mains-fed, heated via a coil in the thermal store

My question is; would it be feasible to connect our existing CH system to such an arrangement, given that it uses micro-bore tubing?

I'd also appreciate any comments on the proposed system, and any tips from anyone who uses / has installed similar.

Thanks in advance...

[Richard Owen]

I'd connect all heat sources directly to the store. I wouldn't bother putting the oil boiler through a coil.

Microbore is no problem being driven from a store.

The last house I did is a big (think small street) 5 bedroom bungalow and the four heating zones are all microbore. Longest run is about 22m (44m there and back.)

[tarrel]

Thanks for the feedback.

Would it be possible to connect the oil-boiler directly to the store?  I'm assuming the store would have to be vented, as the wood burning stove is an uncontrollable heat source.  At the moment the oil-boiler is connected to the pressurised central heating system.  I don't know enough about boilers to know whether than can run either a pressurised or non-pressurised system.  The boiler is a Grant oil-fired combi-boiler, situated outside the house.

On a related subject, does anyone know if any log-burning stoves or range cookers are (or are likely to be) accredited for payment of the Renewable Heat Incentive?

Thanks again.

[renewablejohn]

On the bright side the Otag Bison  pellet micro CHP should be eligible for Fit's on the electric generated. On the downside I think they still cost in excess of 20k but when RHI comes in it should be eligible for that as well.

[tarrel]

Not really interested in pellet, as we have 60 acres of woodland.  Hence we'll definitely be using logs!  Would be interesting to do the payback calculation though, on the combined FIT and RHI payments.

[Richard Owen]

I'd go for a log batch boiler for the main heating.

A couple of people round with us have them now.

They are very efficient converters of wood into heat.

And, if you choose the right one, will qualify for RHI payments.

On the boiler front, check with your manufacturer. I put in an oil fired boiler last year (Worcester Bosch Greenstar) which is supposed to run in a pressurised system. I made a mistake and bought a vented store. The store takes a maximum of 1.5 bar. The property is so big, that to get 1.5 bar when all the systems are up to temperature means its sitting at zero bar when cold. It doesn't seem to make any difference at all. The boiler just works irrespective of what pressure's showing on the gauge.