Thermal store, solid fuel & copper pipe

[oldbutnotdead]

The House of Pain Heating System will have (eventually) big woodburner, maybe thermal solar panels and probably a gas boiler all driving a thermal store (700 litres is what I've been told I need) with an immersion heater in it for emergencies. Output (radiators) will run from the thermal store in the conventional fashion, hot water via a plate heat exchanger in the store.

Question- does all the pipework for the system have to be copper (due to the uncontrolled heat source) or is it just the pipework between woodburner/boiler etc and the thermal store. Specifically, does the DHW piping have to be copper? The Approved Documents don't seem to know about thermal stores, various suppliers I've asked have all been either a bit vague or full of 'our installation team will look after all that'- no they won't, this is an (ill-advised but I'm stuck with it now) DIY refurb so pipework is going in as I do floors & walls for later connection to the thermal store. I'm quite happy with the heating being full copper (and it makes sense given the water in the store could hit boiling point) but since the DHW will be via a heat exchanger with mixer valve I'm wondering whether I can avoid some tricky runs by using plastic?

Ta all (and yes I did have a search and couldn't find the combination- if the Q has already been A'd somewhere then please point me at it)

 

[Dan Robinson]

Primary pipe work and the safety discharge/overflow pipes work will need to be copper/steel. Domestic and system pipe work I see no reason why they can't be plastic once you are a metre or two away from the store.

 

[oldbutnotdead]

Yeah, that's my thinking as well on the hot water side. See what the consensus is, hopefully get a few more interested parties and ideally a reference to some definitive publication

 

[Dan Robinson]

There won't be a definitive publication unless the manufacturer of the store has one.

Other opinions from this site's contributors are welcome, but be mindful of the total nimrods that post with presumed authority - and to be fair, I have limited experienced of solid fuel.... But I have 18 years experience hands on in the industry as a whole.

@Firebrand and @muggles are two here to listen to. If its hard work, or goes by the name of Bernard or JohnD, then think of something more constructive - like a Noddy book .

 

[bernardgreen]

When heating water with solid fuel there has to be a way to dump excessive heat until the solid fuel burner can be shut down. This is normally achieved by dumping hot water to the drains and replacing this with fresh cold water until the solid fuel burner has been shut down. If the mains water supply is reliable then the replacement water can be taken from the mains. With a poor or un-reliable mains supply a cold water store to gravity feed the replacement cold water could be a sensible back up.

Research properly into what is necessary when installing a wood burner of the size you are considering. HETAS is a good source of general information. The various manufacturers will provide information as to safety measures needed for their various types and sizes of wood burning and you may have to restrict the size of the burner to the capacity of the water system.

since the DHW will be via a heat exchanger with mixer valve I'm wondering whether I can avoid some tricky runs by using plastic?

consider the risk of the mixer valve malfunctioning and the risk of there being no cold water to mix with the (over heated ) hot water.

once you are a metre or two away from the store.

If the water in the store is too hot to flow safely through plastic pipe then it will still be too hot after flowing through a metre or two of copper pipe. The requirement for copper tails to a boiler is in case the boiler repeatedly dry fires and its metal work then becomes hot enough to affect plastic pipes. With no water flowing the metre or two of un-insulated copper pipe will dissipate enough heat that the temperature at the joint to plastic pipe will be low enough to not significantly affect the plastic.

If its hard work, or goes by the name of Bernard or JohnD, then think of something more constructive - like a Noddy book .

Dan is a numbers man. He has yet to explain how a boiler can be rated as 122% A rating which, in that form, implies the boiler puts more heat into the water than there is heat produced by burning the gas. The correct format is 122% (Hi) where the (Hi) qualifies the value and reveals the figure of 122% is the result of actual test results being manipulated.

One manipulation process can convert 70% actual measured efficiency to an artificial efficiency value above 90% (qualified ). Good for marketing the boiler, not good news for the person paying the gas bills.

 

[Dan Robinson]

Shut up Bernard.

If you had half a clue you'd be dangerous.

 

[oilboffin]

Nice one dan I fully agree,I have a massive thermal store all my own work but I'm a proper plumber and worked on stores for long time.if I were to give advice I would say contact heatas and be careful of who you take advice from,and I would certainly take no notice of what BG says.

 

[bernardgreen]

I would say contact heatas and be careful of who you take advice from,and I would certainly take no notice of what BG says.

Who are heatus, ? Go on nip in quick and edit your mistake.....

Did you miss the bit where I suggested contacting HETAS ?

Research properly into what is necessary when installing a wood burner of the size you are considering. HETAS is a good source of general information. The various manufacturers will provide information as to safety measures needed for their various types and sizes of wood burning

If you are going to be critical then at least be accurate.

Does your massive heat store connect to a solid fuel burner ?

 

[Dan Robinson]

Not remotely pompous there eh Blowhardgreen?

 

[Hot&Cold]

oldbutnotdead your installation will be tailor made for that property which is good.great stuff.

But as there are many different safety requirements have to be adhered to,i would suggest its not a diydafty install and consider getting it all installed to the current building regulations and a certificate's issued so you know your safe & your property insurance will not impose extra charges or give you the Spanish archer during a claim.
In any claim your property insurance company can ask for that certificate.Believe me.They will.

Its also a legal requirement to have all yes ALL of the installation correct,so its not diy. Sorry.

Good luck and ignore grass.

 

[oilboffin]

My heatstore collects from solid,oil and solar panels.it holds 2000lts and there are removable panels
to allow maintenance.made it myself from 6mm copper fully brazed.And you will note I did not rise to BGs comment I'm better than that.

 

[Corgigrouch GTi]

When heating water with solid fuel there has to be a way to dump excessive heat until the solid fuel burner can be shut down. This is normally achieved by dumping hot water to the drains and replacing this with fresh cold water until the solid fuel burner has been shut down. If the mains water supply is reliable then the replacement water can be taken from the mains. With a poor or un-reliable mains supply a cold water store to gravity feed the replacement cold water could be a sensible back up.

Research properly into what is necessary when installing a wood burner of the size you are considering. HETAS is a good source of general information. The various manufacturers will provide information as to safety measures needed for their various types and sizes of wood burning and you may have to restrict the size of the burner to the capacity of the water system.


consider the risk of the mixer valve malfunctioning and the risk of there being no cold water to mix with the (over heated ) hot water.



If the water in the store is too hot to flow safely through plastic pipe then it will still be too hot after flowing through a metre or two of copper pipe. The requirement for copper tails to a boiler is in case the boiler repeatedly dry fires and its metal work then becomes hot enough to affect plastic pipes. With no water flowing the metre or two of un-insulated copper pipe will dissipate enough heat that the temperature at the joint to plastic pipe will be low enough to not significantly affect the plastic.



Dan is a numbers man. He has yet to explain how a boiler can be rated as 122% A rating which, in that form, implies the boiler puts more heat into the water than there is heat produced by burning the gas. The correct format is 122% (Hi) where the (Hi) qualifies the value and reveals the figure of 122% is the result of actual test results being manipulated.

One manipulation process can convert 70% actual measured efficiency to an artificial efficiency value above 90% (qualified ). Good for marketing the boiler, not good news for the person paying the gas bills.

Back in your box, Bernie....

 

[bernardgreen]

Good luck and ignore grass.

Back in your box, Bernie....

The point is I think out of the box and am not restricted to the box full of training notes that so many "engineers" consider are the only way to think about things.

OK explain what happens when the temperature of the water in the store is close to boiling point and the solid fuel stove is still producing heat into the store. Would you remove the burning fuel from the stove or rely on the air damper to close of the air supply ( think carbon monoxide ) and reduce the heat output from the stove down to a level that can be dissipated from the store and/or central heating radiators.

 

[oilboffin]

The secret is to not build too big a fire in the first place which,you will learn with a couple of boil-ups.What I have now is a nimonic ring with holes in which is inside my stove the fire is built in this and burns very happily away and I've not had a boil-up yet.Bob

 

[Dan Robinson]

The point is I think out of the box and am not restricted to the box full of training notes that so many "engineers" consider are the only way to think about things

As someone's dad once said "self praise us not praise".