Any opinions on my heating system?

[aggy]

Hi, can anyone give me their opinion on the heating system I'm planning?

Solid fuel range cooker with a back boiler downstairs gravity feeding via 28mm pipe a 200 litre thermal store upstairs(i'll get a bigger one when I can afford it) leaving the possibility of adding a heat pump at some point. Underfloor heating downstairs but the manifold upstairs in the same cupboard as the store. 23m2 kitchen as one zone, 48m2 living room split over 2. (I read that pipe runs shouldn't be longer than 100metres and that 100metres will do 25m2). 4 pumped radiators upstairs. The house is in the process of being well insulated.

Is the heat store enough of a heat dump or should the bathroom radiator be gravity fed by t-ing into the 28mm as well?

Does this sound plausible?

Thanks.

 

[igotalake]

that is a very complicated system you are planning which will take a good brain to design and install. i don;t think the manifolds being upstairs should matter but then maybe i'm wrong.

it would be much easier for everyone here to assess what you're talking about if you could supply some photos or drawings with measurements...and if you're thinking of heating that sort of area with a woodburner then you're crazy...

 

[aggy]

Hi, thanks for replying.
I know its complicated, thats why I want advice. I don't know if my brains up to the job without a bit of help. I'll try and cobble together a diagram of what I'm planning. Does anyone else have any views or experience of what I want to do?
Ps. Do you really have a lake?

 

[Agile]

My advice is that unless you are a very experienced heating engineer then you should pay a professional to design a system for you.

Then if it does not work you can blame him!

Tony

 

[aggy]

Agile, I wish I could afford to pay a very experienced heating engineer but I can't. Can anyone comment at least on my underfloor plans. 100m runs, 25m2 per run? Manifold upstairs? Is a heat store enough of a heat dump?

 

[igotalake]

what we need to know is your stove details: make, model, and particularly it's output (colour is not important!).

what will the flow through the underfloor circuits be?

what is the flow through and square meterage of the stove output coil in your heat store?

and yes, igotalake!

 

[Agile]

Since the work you are proposing will have a very considerable cost a small payment to a heating consultant would be a very small percentage of the total cost and would avoid expensive mistakes fitting something that does not do the job.

Heating engineers go on learning courses, spend time working to experienced people and gain their experience over many years doing installations. That breadth of experience is not learnt from asking three questions on a forum.

Tony

 

[igotalake]

i think Aggy said he/she is doing this on a tight budget so calling in a designer may actually be a big chunk of the budget and anyway, i thought this site was called 'DIYnot' !


i'm not a professional heating designer but i'm going to try work this one out so anyone who finds fault with my reasoning or engineering please explain where i'm wrong:

i would say that 100w/m2 would be a reasonable output from your floor circuits. 100 x 75m2 = 7500 watts output.

the thermal store would need to be able to supply this amount plus any losses involved (i don't know how to estimate these) but maybe total output would need to be 10kw.

the input from the stove to the store will need to be able to supply this or more.

if the stove boiler can't supply 10kw via gravity feed you may need a pump as well.

if the input coil that you have in your store can't transfer 10kw to the store then you may need another or a larger heat exchanger.

but if these conditions can be met i don't see why it isn't feasible...

 

[FrankE]

Are you considering this as your primary heating system?
Does that cooker come with a fuel hopper, stoker and extractor?

I think you should contact an engineer (proper CEng, at least IEng type not a plumber) to look into this. They'll be able to tell you fom the outset if it's feasible. If it is, which i doubt, they'll appoint a fitter and you can divest responsibility with them for finding a replacement fitter if it goes pear shaped and the original fitter tries to wash their hands of the project. They'll also hold the contractor to a price. Have a look on the CIBSE site.

I'll PM you details of a company well experienced in bio-mass fuelled heating systems. They can at the very least forward you to a similar company nearer you.

 

[aggy]

Thanks for the replies. I intend to do all the work myself and would like input from anyone with experience of a similar setup.

The stove is a franco belge type 82 904. I cant find the output for it but a smaller one in that range does 7kw so I'm guessing this will do at least 10kw.

In new builds, the heat flow for ufh is about 60W/m2 but I'd expect about 80 W/m2 in our place. The ufh would be a bonus but getting heat into the rads would be the priority. The ufh pipes will be in place for if I add in a heat pump or oil boiler.

This is how I picture it working

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• aggy
• 12 Feb 2010
• 1

( i hope the picture works) There would also be wood burner in the living room for extra heat. It would be a direct system so no heat exchanger in the tank. Unfortunately a UK pension won't stretch to paying a french heating engineer.

 

[Agile]

Je pense que le plupart des systems chauffage sous plancher ne donne plus que cinquant watts par metre carre. Mais ca depende sur le methode de construction.

Tony



Pardonnez moi mais je ne peut pas trouver les accents!

 

[igotalake]

i forgot about the rads...if they are the priority, what output are they?

to FrankE: i wouldn't argue with you when you say that you doubt it would be feasible, but i am interested in this sort of system for myself so i would ask you to explain the reasons why you have come to that conclusion...

 

[mointainwalker]

In my opinion your ideas of heat output per m2 are completely wrong.

Figures of W/m2 are being bandied aroud as if this were some kind of given rather than depending on pipe spacing which is not mentioned anywhere except implicitly where 25 m2 per circuit are spoken of.

AFAIK 100W/m2 is achievable with normal input temps ( 40-45 C) with pipe centres at 10 cm. This means one circuit will cover 10 m2 not 25 m2. You could have a 25 m2 circuit but with an output of 40 W/m2 approx.

This apart you must not forget the extra few metres you will need to get to and from the manifold .

Using my figs this would mean at least 7 circuits and I don't know if you can get such a big manifold so that might mean two.

Do you have a reasonabe amount of space in the cupboard for the manifold and pipes ? They are not small and you need space around it/them to install them and feed pipes in a straight line on to the connections.

Which part of the Republique are you in and have you decided where to source any bits yet ?

@ Agile. UFH = plancher chauffant and metre carre not cube

 

[aggy]

This is interesting. I think there are two issues emerging,

1 how the ufh is laid out.
2 the overall idea.

1 I dont think i need 100w/m2 downstairs. The house will be quite well insulated, a wood burner in the living room to make it toasty and the cooker in the kitchen which is feeding the ufh giving heat out directly into the room. I'm working on 3 runs of 100m using 16mm pipe at 20cm.

2 Whats wrong with the overall idea of back boiler, heat store, rads and ufh.

Igotalake (can I call you igo?) I dont see any reason why it wouldn't work with a bit of tweaking.

Mountainwalker, I'm in north vienne.

 

[Agile]

In England we work on the basis of about 50w/m² for UFH.

This one will give you a free quote!

http://www.confort-chauffage-clim.com/1/rubrique.php3?id_rubrique=24

Or you could call Les Services Agiles:-

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• Agile
• 4 Apr 2009
• 29