Underfloor heating, any plumbers? - Page 4 - SV650.org

Luckypants · 22-10-09, 10:42 PM

Chris, what you describe wanting to do is what I have in my house, although it's been designed in. My stove has a built in boiler (Charnwood CW50B) and is linked into a traditional cylinder / CH system by means of a Dunsley Neutraliser. So I have some understanding how these things work, because I have made improvements over the years and have planned several others. My next house will use a similar system, if I get my way.

The advice so far is good, especially the bit about controlling the fire and the hot water produced. It is imperative that excess heat in the fire's boiler is dumped somewhere AND also that the fire can be controlled to prevent boiling in the boiler, if the boiler has enough steam it will explode VERY badly - my father in law was a plumber and always relates the horror story of one that exploded.

Most of the solutions to adding a stove to a heating system rely on some clever gizmo such as my neutraliser, a Heating Innovations H2 panel, thermal store or other such expensive trickery. These tend to be designed to work with traditional systems, not much use with a combi. My idea would be introduce heated water from your stove on the return to your boiler. This has the effect of reducing the frequency the combi fires to keep the radiators hot, thus saving gas. If you have TRVs on almost every radiator it may be enough to keep the house at a stable temperature once warm. NOTE you must leave at least one rad uncontrolled to act as a heat dump if the fire is burning but all TRVs have closed!

However, I understand that combi boiler radiator systems are pressurised and I'm not sure that any of the solutions to achieve getting the hot water into the return would suitable or safe. I guess you need someone who knows about combi's to answer that.

skeetly · 22-10-09, 10:44 PM

When we have done ufh there is usually a 'mixing' manifold that mixes in some of the returning (gone cold) water in with the hot water going into the loop. Theres a thermostat to gauge this. It helps to get th most from the fuel used.
A 'simple pump the hot water round a loop' type system that you envisage might result in the circulating water getting too hot for the plaggy pipe to handle.....
This would be a failure

skeetly · 22-10-09, 10:46 PM

Quote:

Originally Posted by Luckypants

Dunsley Neutraliser.

He speaks the truth. We just fitted one of these to combine a rayburns output with a giant oil fired boiler for a mansion sized house.

Power is nothing without control.................

Luckypants · 22-10-09, 10:50 PM

Well to be honest a nuetraliser is old hat, but when retro fitting it can be slotted in quite easily.

Good point about melting the placky pipe Mark!

skeetly · 22-10-09, 10:53 PM

Quote:

Originally Posted by Luckypants

Well to be honest a nuetraliser is old hat, but when retro fitting it can be slotted in quite easily.

Good point about melting the placky pipe Mark!

As old hat as it may seem it works a treat

You can still buy them too.......300 quid.

Luckypants · 22-10-09, 10:56 PM

Sorry, didn't mean it didn't work. I have more ambitious plans for my next multi-source heating system is all.

skeetly · 22-10-09, 10:58 PM

Quote:

Originally Posted by Luckypants

Sorry, didn't mean it didn't work. I have more ambitious plans for my next multi-source heating system is all.

Do tell!

Luckypants · 22-10-09, 10:59 PM

Quote:

Originally Posted by skeetly

Do tell!

I think we have hijacked Yorkie's thread enough, PM / MSN me

yorkie_chris · 22-10-09, 11:01 PM

Hmmm.
SV thermostat housing? Chop a radiator in half and weld it up so it will fit between joists, when the thermostat pops it will heat the radiator not the pipe coils.*

But, with an open system it will never get over 100c anyway (with the tank in the loft I reckon that is a 7m head so only about 68kPa, negligible effect on boiling point). So, depending on what the manufacturer says I think the tubing should be able to handle the max temperature OK.

*My stepdad's a sparky, he says the first use of underfloor heating he saw was a guy bolting a pair of normal radiators underneath the floor!

The problem is, what happens if the pumps switching is delayed, there can be very little convective movement because the stove is above the cooling coils.

I don't think an explosion is possible under steady state, because the system is not sealed. But, a large amount of steam could be generated when the pump is switched on when the stove is hot and has formed a steam bubble in the boiler. This I don't like.

yorkie_chris · 22-10-09, 11:01 PM

Quote:

Originally Posted by Luckypants

I think we have hijacked Yorkie's thread enough, PM / MSN me

Nah chat away! Engineering geek here

22-10-09, 10:42 PM	#31
Luckypants Moderator Mega Poster Join Date: Jul 2003 Location: Nr Ruthin Posts: 7,058	Re: Underfloor heating, any plumbers? Chris, what you describe wanting to do is what I have in my house, although it's been designed in. My stove has a built in boiler (Charnwood CW50B) and is linked into a traditional cylinder / CH system by means of a Dunsley Neutraliser. So I have some understanding how these things work, because I have made improvements over the years and have planned several others. My next house will use a similar system, if I get my way. The advice so far is good, especially the bit about controlling the fire and the hot water produced. It is imperative that excess heat in the fire's boiler is dumped somewhere AND also that the fire can be controlled to prevent boiling in the boiler, if the boiler has enough steam it will explode VERY badly - my father in law was a plumber and always relates the horror story of one that exploded. Most of the solutions to adding a stove to a heating system rely on some clever gizmo such as my neutraliser, a Heating Innovations H2 panel, thermal store or other such expensive trickery. These tend to be designed to work with traditional systems, not much use with a combi. My idea would be introduce heated water from your stove on the return to your boiler. This has the effect of reducing the frequency the combi fires to keep the radiators hot, thus saving gas. If you have TRVs on almost every radiator it may be enough to keep the house at a stable temperature once warm. NOTE you must leave at least one rad uncontrolled to act as a heat dump if the fire is burning but all TRVs have closed! However, I understand that combi boiler radiator systems are pressurised and I'm not sure that any of the solutions to achieve getting the hot water into the return would suitable or safe. I guess you need someone who knows about combi's to answer that. __________________ "Your Viffer sounds like it is raising hell! Spot on." - Witchery 17/4/08 Snow Plough Appreciation Society - Member #3

22-10-09, 10:44 PM	#32
skeetly Member Join Date: Jan 2008 Location: betws y coed Posts: 749	Re: Underfloor heating, any plumbers? When we have done ufh there is usually a 'mixing' manifold that mixes in some of the returning (gone cold) water in with the hot water going into the loop. Theres a thermostat to gauge this. It helps to get th most from the fuel used. A 'simple pump the hot water round a loop' type system that you envisage might result in the circulating water getting too hot for the plaggy pipe to handle..... This would be a failure

22-10-09, 10:50 PM	#34
Luckypants Moderator Mega Poster Join Date: Jul 2003 Location: Nr Ruthin Posts: 7,058	Re: Underfloor heating, any plumbers? Well to be honest a nuetraliser is old hat, but when retro fitting it can be slotted in quite easily. Good point about melting the placky pipe Mark! __________________ "Your Viffer sounds like it is raising hell! Spot on." - Witchery 17/4/08 Snow Plough Appreciation Society - Member #3

22-10-09, 10:56 PM	#36
Luckypants Moderator Mega Poster Join Date: Jul 2003 Location: Nr Ruthin Posts: 7,058	Re: Underfloor heating, any plumbers? Sorry, didn't mean it didn't work. I have more ambitious plans for my next multi-source heating system is all. __________________ "Your Viffer sounds like it is raising hell! Spot on." - Witchery 17/4/08 Snow Plough Appreciation Society - Member #3

22-10-09, 11:01 PM	#39
yorkie_chris Noisy Git Mega Poster Join Date: Apr 2007 Location: Halifax/Leeds Posts: 26,645	Re: Underfloor heating, any plumbers? Hmmm. SV thermostat housing? Chop a radiator in half and weld it up so it will fit between joists, when the thermostat pops it will heat the radiator not the pipe coils.* But, with an open system it will never get over 100c anyway (with the tank in the loft I reckon that is a 7m head so only about 68kPa, negligible effect on boiling point). So, depending on what the manufacturer says I think the tubing should be able to handle the max temperature OK. *My stepdad's a sparky, he says the first use of underfloor heating he saw was a guy bolting a pair of normal radiators underneath the floor! The problem is, what happens if the pumps switching is delayed, there can be very little convective movement because the stove is above the cooling coils. I don't think an explosion is possible under steady state, because the system is not sealed. But, a large amount of steam could be generated when the pump is switched on when the stove is hot and has formed a steam bubble in the boiler. This I don't like. __________________ Currently Ex Biker Now rebuilding a 63' fishing trawler as a dive boat

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
.Org Plumbers?	Dave20046	Idle Banter	213	09-04-12 08:51 PM
Any Plumbers in the house???	DF!	Idle Banter	3	02-12-08 09:58 PM
Underfloor Heating	Gazza77	Idle Banter	9	10-06-08 08:17 AM
Any plumbers on here?	ukgooner	Idle Banter	15	27-04-08 11:50 AM
Plumbers help with my new bathroom	furrybean	Idle Banter	27	06-02-07 09:23 PM