combined system; wood boiler, solar, and mains gas boiler ?

[jamesg]

Excellent threads so far. I'm in a very similar situation needing advice; Have also posted this in 'Biomass General'

At Present my situation is; 3 bed 1978 semi, cavity filled + topped up loft insulation, on mains gas.
No radiators in house, just a woodburner(without backboiler) in open plan downstairs room, & an old instantaneous gas water heater for tap hot water. No header tank in loft, no hot water storage cylinder.

Want to replace old gas water heater for a modern combi or condensing boiler, to run my newly installed underfloor heating circuit in the kitchen/dining extension, and 3 radiators to distribute heat upstairs better than the woodburner does.

Later(in a few years when gas increases in cost) want to replace current woodburner with one that has an integral boiler, and have this plumbed into the underfloor heating, and 3 radiators, via a storage tank with coils.
Also want the option of introducing solar thermal into system as well (the solar thermal panels will be on a lower extension roof, so a feeder tank in the loft is possible for a vented system)

I don't want to buy the thermal storage tank now, only when I decide to introduce the wood stove boiler and solar later. I don't mind buying a feeder tank for the loft if a vented system is better.

Question is ?  What type of gas boiler should I have installed now.?
An open vented type, with a feeder tank in the loft (is that a condensing boiler?), or a combi sealed boiler ?
or any other type of gas boiler that suits this scenario.

Many thanks if anyone has a similar future proofing situation, or can help. Am in Mid Somerset.

[desperate]

Hi James, now that's spooky, I'm sure I just answered your post......................

Desp
Strange echo cho ho o around here

Yo James welcome...............

check out my CRAC thread on the show us yours board, we have a solar/woodburner/gasser system that works quite well, gas bill gone down from 900/yr to 200/yr.
We used a Worcester Bosch system boiler, that is a sealed pressurised ch and hw system. All domestic boiolers are condensing nowdays the difference is the plumbing system attatched to it, a combi supplies instant hot water on demand, a regular boiler supplies heat to a hot water cylinder and ch, and has an open vented system, a system boiler supplies a hot water cylinder and ch with a pressurised system.

Personally I think a combi would struggle to satisfy the hot water needs in a 3 bed house,, multiple demand leads to low flow situaations sometimes, and are difficult to integrate with a solar system, but they are the simplest and cheapest systems to fit. A system boiler with a hot water cylinder give you the most possibilities for unstandard plumbing designs such as wood burners and solar panels.

Lots of design work needed

[dhaslam]

In the long term you will need a decent sized heat store  and header tank plus  non-combi  gas boiler.     However it would be better not to buy something now that you would later have to remove so   it  might be better just to get  a condensing combi boiler   now and then get a decent  sized store later and at that stage you could just use the heating part of the boiler.   The alternative  might be to install a low cost  conventional  cylinder,  with header tank,   for hot water now.  It would be heated by the gas boiler through the coul. Later you could  have a separate  store that would combine solar, stove and gas  inputs and heat the DHW cylinder by  transfer from the store.      The latter is what  I have  except that the main solar  input (from evacuated tubes)  is to the DHW cylinder.    

[jamesg]

Thank you to the last two threads.
We are a small family (2 adults and 1 young child) and do'nt all have separate baths/showers at the same time, so I regard us as low users of DHW, so feel a combi could provide for our needs if chosen.
I am more interested in the space heating capability, and as the stairs are in the open plan living area, heat does migrate upstairs, but not quite enough, so the reason for 3 small radiators, upstairs.

In a vented system, is it the central heating pipe work that is vented to the header tank in the loft, or is it the boiler?
Can I have a vented system( with the header tank in the loft) , with a condensing boiler, without the heat storage tank, and run domestic hot water on demand from the gas boiler. The  3 coil heat storage tank would be added in a few years.

Is a vented system a better option, as there are more wood stove boilers available for later plumbing in.
I have been told by boilerstoves in devon (a good website) that there are a few pressurized wood boiler stoves available, and probably more in a few years time.

I am not a plumber, so I am having to get up to speed on this, and understand the constraints, so I can brief the plumber about how I see this working.

[desperate]

Hallo James,

A combi would probably supply your hot water and heating needs OK with just the three of you, but incorporating solar and the stove would be more difficult and more expensive. The regular boiler is vented to the header tank, or in reality the pipework very close to it is, the exact position of the feed and vent pipe is critical to the wellbeing of the whole system. The only gas boiler that supplies hot water on demand without a cylinder is a combi type, nearly all of which are designed to run a sealed and pressurised system. Personally I don't like vented systems, they are prone to problems that may go unnoticed or ignored which cause all sorts of damage. A sealed system shows up any problems of this sort with a pressure drop, which forces the issue.

 Finding a plumber who can take on your system may be quite difficult, it may be worth specifying what you need from your system and then getting plumbers to cost and design a system for your perusal, then you could post up those suggestions here. There are many ways to set up a system to combine solar/woodburner/gas and all will have their merits and drawbacks, but without looking at your specific layout and demands it is quite difficult to be  specific.

In order of complexity and cost, ROUGHLY your system would go:-

1 Combi and dry woodburner no solar
2 Combi and dry woodburner solar with preheat to combi
3 Regular/system boiler and dry woodburner solar and hot water cylinder
4 Regular/system boiler woodburner with boiler and solar with hot water with dunsley or system link
5 Regular/system boiler woodburner with boiler and solar with hot water cylinder and thermal store.

Or something similar, you could start from 4-5 grand for option 1 up to 15 grand or more  for option 5

Lots of homework to do, but it is worth it to get your system right.

Desp

[jamesg]

Hello Desperate,
Thank you for your compehensive advice, and recommendations.
Hopefully the plumber will be able to design the system, and implement in a phased way.
James.

[Solal]

Good moaning James.
I don't know if anyone has mentionded it  but consider a combi  that accepts  solar pre heated water.