Oil and Multi fuel Stove Linkup - Part 1

[Killy Bing]

You know what, please do this.

i want to see how bad the thermal shock will be on the news......

 

[Gray0689]

1KW - 2.5 KW heat leak rad vs 30 / 50 / 100 KW Heat exchanger ? cant really see your point ?
The thermostatic valve opens at 95 degrees allowing cold mains water through exchanger and to drain. No power required - how exactly is that silly. Trying to dissapate 10KW of heat through a 2.5 KW heat leak rad sounds silly to me.

I'm out

 

[dlm4473]

Contravenes the energy eficiency part of the building regs.

Also what happens when the valve fails?

So does a heat leak radiator ! but as its a safety device its allowed.

If the valve fails the flow from the stove boils and overflows into the F&E tank (Vented !). Which can and does happen often using only a heat leak rad.

And for that to happen it would need - a power cut to remove the pumped circuit to rads (heat leak), failure of the stove thermostat which controls the draft (and therefore its output), a 200l tank of water to have reached 95 degrees.

SIMONG
Yes there are, and this is one of them - as i stated its main use is to allow solid fuel connections to unvented cylinders.

Killy Bing - what exactly are you talking about ? you obviously have not read the thread or understand the system i'm discussing - as i asked you before please explain to me how you believe that a 1KW heak leak can dissipate 10KW of energy from a stove during a power cut ? What do you think happens when the water in your heat leak rad reaches 95 degrees ?

 

[Dotty]

I'm out

It's another of those threads I gaze at with morbid fascination!

 

[dlm4473]

So is the heat exchanger fed off the store via a pump? And gravity off the stove into the store?

Just to clarify - there will be TWO heat exchangers on the store.

One smallish one (15/25KW)pumped from store on one side and pumped by CH pump on the other. This will feed the CH and DHW circuits (using thermostatic valve to control flow temp)

The SECOND heat exchanger (50KW or so) is installed purely as an overheat protection. It will be controlled by watts sts20 or similar. As it will be on the gravity circuit it will not need pumped from the stove, as valve is connected to mains cold, that requires no pump. Using this sort of device would facilitate connecting a store to an unvented tank - although mine will be vented.

 

[Gray0689]

It's another of those threads I gaze at with morbid fascination!

It amazes me john that when someone asked for advice
Then just totally does the opposite lol
Sure let them do what they want it's not my house lol

 

[Nostrum]

Can't quite see how the second heat distributing heat exchanger will work effectively. The cold water will cool the heat exchanger, but the stove will carry on heating the store? The heat loss will be negligible.

unless the bottle of cheap 'meal deal' champagne I'm drinking is hindering my reading abilities?

 

[Gray0689]

Can't quite see how the second heat distributing heat exchanger will work effectively. The cold water will cool the heat exchanger, but the stove will carry on heating the store? The heat loss will be negligible.

unless the bottle of cheap 'meal deal' champagne I'm drinking is hindering my reading abilities?

Vintage krug it is then lol

 

[Nostrum]

Smart price bollinger I think.

 

[dlm4473]

Can't quite see how the second heat distributing heat exchanger will work effectively. The cold water will cool the heat exchanger, but the stove will carry on heating the store? The heat loss will be negligible.

Hot input to heat exchanger is main gravity flow - cooled output to gravity return . Valves stays open as long as water temp >95 degrees. Cooled return will speed up gravity flow which in turn speeds cooling. A 50KW heat exchanger will cool 5 times faster (with sufficiant flow) than the stove (10KW) can heat. This method will ensure the water cannot boil - which a a heat leak can only "help" to prevent.

This system is already incorporated into off the shelf thermal stores - xcel heat bank is one that i know of. wont let me post links but youl find it on heatweb. To quote from their site

"Another unique aspect of the Xcel Heat Bank (again, patented by us so unavailable anywhere else) is its ability to protect from overheating, even during a power cut. This system was designed primarily for systems connected to a wood burner. It is needed because wood burners provide a large amount of energy, and they don't turn off, even when there is a power cut. As such they easily have the ability to boil the water in a thermal store if there is no other form of protection.
The standard approach is to use a heat leak radiator - located higher than the wood burner so that heat generated in the wood burner circulates naturally (thermo-syphon) to the radiator where heat is dissipated and the cooled water drops back into the wood burner. This is fine providing:

1. 
   [*=1] The wood burner is thermostatic, and slows its burn rate down when it gets hot.
   [*=1] The heat leak radiator is large enough to dump the output of the wood burner.
   [*=1] A location can be found above the wood burner for a dedicated heat leak radiator.

The problems start occurring when not all of these criteria can be met, and given that most wood burners are not thermostatic and have an output of approx 9kW to water, the chances of dedicating 9kW of radiators (three large double convectors) to this function becomes impossible.
The protection system on the Xcel works on the basis that the heat can circulate from the wood burner to the Heat Bank naturally using thermo-syphon (gravity) circulation. The Xcel is fitted with a heat exchanger in the top, and if the temperature of the water in the store ever goes over 95°C then a mechanical valve opens up to allow cold mains water to pass through the heat exchanger and out to drain, cooling down the stored water as it does so. The heat exchanger can extract over 12kW of heat and as such is suitable for all types of wood burner, and in many instances is the only way that the latest building regulations (now covering vented systems) can me met when using a wood burner."

Hence the reason i am confused at the advice being given - i'm not ignoring anyones advice i'm trying to understand it.

 

[Dotty]

The advice is get someone in who knows what they're doing. You don't need to understand the system.

You just need faith in it. And what you're looking to do I wouldn't put faith in if I were you.

 

[dlm4473]

The advice is get someone in who knows what they're doing. You don't need to understand the system.

You just need faith in it. And what you're looking to do I wouldn't put faith in if I were you.

The only problem there croppie is that I would struggle to have faith in the people that say they "know what there doing" when they ;

1) cant answer a simple question i.e. how does a 1KW heat leak rad dissapate heat from a 10KW stove
2) Whilst professing how knowlegable they are - are apparently unaware that this system is fitted to off-the-shelf thermal stores - presumably (but i could be wrong) passing all relevant standards inc. building control and WRAS.
3) Appear to think that Danfoss (and other manufacturers) who designed and made these valves specifically for use with heat exchangers for overhead protection on solid fuel heating systems are "silly" and don't know what they are doing.

Would you have faith in that person ? or the system they installed ?

 

[Gray0689]

The only problem there croppie is that I would struggle to have faith in the people that say they "know what there doing" when they ;

1) cant answer a simple question i.e. how does a 1KW heat leak rad dissapate heat from a 10KW stove
2) Whilst professing how knowlegable they are - are apparently unaware that this system is fitted to off-the-shelf thermal stores - presumably (but i could be wrong) passing all relevant standards inc. building control and WRAS.
3) Appear to think that Danfoss (and other manufacturers) who designed and made these valves specifically for use with heat exchangers for overhead protection on solid fuel heating systems are "silly" and don't know what they are doing.

Would you have faith in that person ? or the system they installed ?

Yep probably more than you

 

[dlm4473]

Can't quite see how the second heat distributing heat exchanger will work effectively. The cold water will cool the heat exchanger, but the stove will carry on heating the store? The heat loss will be negligible.

Hot feed to Heat exchanger is on gravity flow (as is sensor) Cooled water from exchanger returns to gravity return. Difference in temp will increase gravity flow (which would just about stall at 95 degrees) more cooling performed by exchanger the faster gravity flow through exchanger - the faster cooling takes place. When temp goes below 95 in top of gravity flow circuit (hotest part of circuit) the sensor shuts off the valve.

 

[Gray0689]

Dlm
What is your profession

 

[Killy Bing]

Hot feed to Heat exchanger is on gravity flow (as is sensor) Cooled water from exchanger returns to gravity return. Difference in temp will increase gravity flow (which would just about stall at 95 degrees) more cooling performed by exchanger the faster gravity flow through exchanger - the faster cooling takes place. When temp goes below 95 in top of gravity flow circuit (hotest part of circuit) the sensor shuts off the valve.

.......so at 95 degrees on one side of the heat exchanger.....you intend to flush the other side with mains water to reduce the temp?

correct?

 

[dlm4473]

Yep probably more than you

I thought you were "out" if your going to nothing but critisise why keep posting ? You gave me advise to check out with building control - which I've done - but you can't even wait for the response before you say the system and me are incapable of doing the job !

You havn't even attemped to respond to any of the three questions above - that would be giving advice! so tell me how does a heak leak radiator of 1KW stop the water boiling in a system that is outputing 10KW ?

 

[Gray0689]

.......so at 95 degrees on one side of the heat exchanger.....you intend to flush the other side with mains water to reduce the temp?

correct?

Yep think he does
So let's sat you cool hex without busting it from the shock of the incoming cold mains
So hex gets cooled
What cools the stove as it is sitting at 95
Fire still lit still producing uncontrolled heat
It starts to boil then flashed to steam as the hex is not dissipating the heat
Increasing its volume by (come on op you should know this one)

I wouldn't like to be to near it myself

 

[Gray0689]

I thought you were "out" if your going to nothing but critisise why keep posting ? You gave me advise to check out with building control - which I've done - but you can't even wait for the response before you say the system and me are incapable of doing the job !

You havn't even attemped to respond to any of the three questions above - that would be giving advice! so tell me how does a heak leak radiator of 10KW stop the water boiling in a system that is outputing 10KW ?

Because I don't need to tell you
YOU should already know that answer
Plus it's not 10kw radiator
Check your facts

 

[Gray0689]

I thought you were "out" if your going to nothing but critisise why keep posting ? You gave me advise to check out with building control - which I've done - but you can't even wait for the response before you say the system and me are incapable of doing the job !

You havn't even attemped to respond to any of the three questions above - that would be giving advice! so tell me how does a heak leak radiator of 10KW stop the water boiling in a system that is outputing 10KW ?

But yes your correct and it's not criticism just my opinion
I'm out lol