Multifuel stove central heating sytem. HELP

[8MrBlister8]

Hi im new to the forum and would really appreciate some advice. I have laready tried searching with little or no luck with what im trying to do. I live in a small two bed cottage which has no central heating. The heating is currently provided by an aged 6kw hunter woodburner. this is shortly to be replaced with an 11kw multifuel stove with back boiler. My hot water is provided by a boiler in the attic and so i have no emersion tank. The back boiler on the wood burner will be 3kw. What i am looking to do is run a completely seperate gravity fed system e.g. with no central heating pump and not in anyway connected to my existing hot water system.
My thinking is that as the system is only 3kw 10.5 btu that it should self pump. there will be an expansion tank in the attic. Is this system workable? i have spoken to a couple of people, one who runs two radiators on this type of system and another who runs his with a pump but seemed to think i could do it unpumped.

I understand that i should not use TRV's with this type of system either. Essentially i am looking to install the simplest possible 3 radiator heating system possible.

Also i am intending to do this using 15mm piping, my understanding is that for heating under 4.5kw 15mm is perfectly suitable. is this correct?

Any help/advice greatfully recieved.

Blister

 

[agbagb]

Have you considered just running the fire with your internal doors open. Even over the last few really cold days we have been running our wood burner (not at full 7.5kw output) to heat our 5 bed victorian house 9ft ceilings etc. Maintaining 18 degrees in the coldest bed room.
Just an idea for you to think about. All the radiator system does is transfer the heat around. If you can get air to circulate it will do it just the same.

 

[oilman]

Don't bother with the wet route, it's a PITA when it goes wrong, and it WILL, just look at the postings on this forum

We have what was a cottage, added a sizable extension and we now have a fair size house (4beds + 2 attic rooms etc), Victorian, draughty, single glazed and other desirable attributes.

The 11kW stove will be MILES too big for you, we have a 5kW with no boiler and it's more than enough. We have an electric 30A aga and a storage heater and an immersion heater in the HW tank. That's it.

Maintenance costs naff all, sweep chimney, replace immersion element every 6 years. House is used all day, total elec bill less than £1100pa, wood £150.

The only problem you have is that Hunter. We had one too. It ate wood and gave no heat. Sold it and got a http://www.clearviewstoves.com/pioneer400.htm model. Uses very little wood and cooks the place in minutes.

 

[8MrBlister8]

Thanks for the replies

Yes the hunter is awful, its rated as being 6.5kw but even when its running at full tilt it seems to provide almost no heat, that's why i went for an 11kw. I have recently been to stay at a friends house that has a very good 10kw and the difference was emmence. the main reason for wanting to do the central heating is that i have already ordered the back boiler with the fire! argh!!!

We have just had to house fitted with hard wood double glazing so that should help a bit. I have also converted the attic, do you think that the 11kw will be man enough for this without the rads.

floor plan is open plan kitchen sitting room containing stairs and front door(4x10m) the next floor is the same foot print with the bed roms and the bathroom with a second staircase coming from one of the bedroms to a 4x5m attic room

 

[oilman]

the main reason for wanting to do the central heating is that i have already ordered the back boiler with the fire! argh!!!

Easily fixed...........cancel it!!!

It is not necessary (or desirable) to heat the whole of the house throughout the year. As the weather gets colder, just migrate to fewer rooms eventually down to the ground floor, and wait till it warms up.

You already have sealed double glazed windows. Not a good move IMO. Condensation will not now occur on the window panes, but within the fabric of the building. Coupled with fewer air changes, there is a better chance of mould growth.

Heating the upstairs as well could be bad news for your roof Why? Warm air holds more moisture, when it gets to a cold place (roof space) it can cool enough to cause condensation. We have a door at the bottom of the stairs, no heating upstairs, plenty of draughts, and everything is sound, and we are healthy. Live in a warm sealed house, you could have mould growth, plenty of bugs floating around and a decaying building. Not EVERYTHING modern is actually better.

 

[Norcon]

I don't see condensation as being a problem. At least not in the room housing the stove as ventilation will be self induced through the operation of the flue.

 

[8MrBlister8]

I think perhaps the best thing to do would be to ask the firm doing the boiler for me to cap it off and then if i decide that the heat output from the fire isnt enough then i can install the rads.

The company in question claim that the heat generated by there 3kw boiler does not cause any heat loss from the fire itself. im a little dubiouse about this but they claim that because of the way the backboiler is fitted it is heated with heat which would other wise be lost.

 

[oilman]

I don't see condensation as being a problem. At least not in the room housing the stove as ventilation will be self induced through the operation of the flue.

Condensation is a problem because hot air rises. Hot air can hold more moisture than cold air. As the air gets further away from the heat source it gets cooler. The cooler it gets the less moisture it can hold. Sooner or later it will reach the temperature where it can no longer hold all the water it carries. Then it condenses.

Condensation is a huge problem in buildings and causes a lot of damage.

 

[agbagb]

Oilman, I'm currently making DG sliding sashes and I can see the condensation becoming a problem for me. Instead of puddle on the window ledges, I'll have damp forming behind wadrobes etc. I can see my next project being HVAC (I think) with a heat exchanger.
Oh well it'll keep me busy.

 

[8MrBlister8]

Condensation is an issue which i have already come across and like many others i simply have to deal with it by using a dehumidifier. I have the dehumidifier on a timer switch which comes on when i go to work. its not a particularly good one but i still get about 2ltrs of water a day out of it. we still get damp behind wardrobes etc, but had this before double glazing anyway!