Oil and Multi fuel Stove Linkup - Part 1

[dlm4473]

View attachment Heating 01.pdf

Hello all,

I am looking for advice, insparation or just constructive critisim !

Currently renovating a house and will be installing a multi fuel boiler stove (Charnwood LA45iB - 10KW to heating, 2.5 to room).

Current heating is Danesmoor 15/19 oil boiler pumped to vented tank (on ground floor - hot flow rate is very poor). I have an ACV 160l unvented cylinder to solve this problem which I need to install asap (to get on with other tasks). My intention is to convert boiler to sealed system and install the tank BUT have pipework ready to go for installation of stove and buffer. This to avoid re pipping in a cramped cupboard space.

I have not yet designed pipework for Stove/Buffer (that will be part 2!) - but intend to extract heat from buffer with a Heat exchanger (thus keeping sealed system for rads and boiler).

Ideally the system will be as flexible and economic to run as possible so i do not want to prioritise boiler over stove or vice versa.

House is bungalow, approx 150msq with little room in loft. Insulation will be 90mm kingspan wall, 70mm kingspan floors and 400mm fibre in loft.

Attached at top is my current plan for installing the Water cylinder, - I would appreciate all and any views on the subject.

Thanks

 

[snowhead]

G3 qualified?

 

[dlm4473]

G3 only required in England and Wales snowhead

 

[Gray0689]

View attachment 17334

Hello all,

I am looking for advice, insparation or just constructive critisim !

Currently renovating a house and will be installing a multi fuel boiler stove (Charnwood LA45iB - 10KW to heating, 2.5 to room).

Current heating is Danesmoor 15/19 oil boiler pumped to vented tank (on ground floor - hot flow rate is very poor). I have an ACV 160l unvented cylinder to solve this problem which I need to install asap (to get on with other tasks). My intention is to convert boiler to sealed system and install the tank BUT have pipework ready to go for installation of stove and buffer. This to avoid re pipping in a cramped cupboard space.

I have not yet designed pipework for Stove/Buffer (that will be part 2!) - but intend to extract heat from buffer with a Heat exchanger (thus keeping sealed system for rads and boiler).

Ideally the system will be as flexible and economic to run as possible so i do not want to prioritise boiler over stove or vice versa.

House is bungalow, approx 150msq with little room in loft. Insulation will be 90mm kingspan wall, 70mm kingspan floors and 400mm fibre in loft.

Attached at top is my current plan for installing the Water cylinder, - I would appreciate all and any views on the subject.

Thanks

Sounds like a plan
You will need some sort of gravity heat leak for when house is up to temp
Simple cylinder stat on buffer wired to pump heat exchanger then pump out to rads ect
Can't see your plan
36x18 direct cylinder be plenty

 

[dlm4473]

Thanks, As store will be in loft space, I am proposing, instead of heat sink, another heat exchanger fed with mains cold to cool down tank on overheat using thermostatic let-by valve at 95 degrees or so. Also considering backup power supply to keep things going in a power cut - this more for the comfort side of things rather than safety - but all the same one more level of safety.

 

[Gray0689]

Thanks, As store will be in loft space, I am proposing, instead of heat sink, another heat exchanger fed with mains cold to cool down tank on overheat using thermostatic let-by valve at 95 degrees or so. Also considering backup power supply to keep things going in a power cut - this more for the comfort side of things rather than safety - but all the same one more level of safety.

Can't see that way passing building control

 

[albatross]

It seems overly complicated to me.
Fit a thermal store in the loft. Connect stove and boiler to it. Open system. Forget heat exch./unvented cyl/motorised valves/bypass. Thermal store will act as a buffer and a heat sink

 

[Gray0689]

It seems overly complicated to me.
Fit a thermal store in the loft. Connect stove and boiler to it. Open system. Forget heat exch./unvented cyl/motorised valves/bypass. Thermal store will act as a buffer and a heat sink

The hex is only if it's wanted to keep both systems separated
Your way is good too

 

[dlm4473]

It seems overly complicated to me.
Fit a thermal store in the loft. Connect stove and boiler to it. Open system. Forget heat exch./unvented cyl/motorised valves/bypass. Thermal store will act as a buffer and a heat sink

One of the problems is that there is no room (or money!) for the size of store that would be needed. What i'm basically doing is splitting a thermal store in two and seperating Heating from water = 2 shorter tanks. At the same time the systems are kept seperate as to be honest I am unsure how much either system will be used. I don't see the point in heating an entire thermal store (extra 300l or so) with an oil boiler - when i can just heat the rads directly, also without extra heatloss of tank and pipework.

Have valves, stats pumps etc lying around, no cost. heat exchangers £20 - 30 on ebay (SH) only expense I can see will be safety valves,overheat valves and loading valve. An off the shelf thermal store can't compete with that .

Can't see that way passing building control

This is what I mean (kind of) - this came from a solid fuel association manual as an example of "additional overheat protection". The same thing can be achieved with a HE , negating the need for extra coil in tank. Cold mains in - Discharge to drain. A heat exchanger/ overheat on gravity circuit, would also allow store to be lower or at same level as the stove, store would obviously be on a pumped circuit.

I struggle with the heat leak radiator thing i.e. -Assuming worst case scenario - house upto temp (rad valves closed) and water cylinder upto temp and store upto temp - (ignoring the fact that the stove has its own thermostat) I really dont understand how a heat leak rad of between 1KW and 25% total output [depending which advice you take] can dissapate 10KW of heat from the stove? Using an overheat system with HE ensures you can can dissapate all excess heat completely . Depending on size of HE which could be 30, 50 or even 100KW you can do it extreemly fast too. At 95 degrees this would prevent overheat before the P/T relief valve opens.

 

[Gray0689]

Are you planning to stay in this house or ever move
If it's not done to a recognised building control method you won't be able to sell house
If anything goes wrong your insurance most probably won't pay out either
Just my opinion

 

[dlm4473]

Good point - I had assumed that as long as requirements for safety were met, it wouldnt matter how. :sweatdrop: . I would have thought, especially as idea came from "solid fuel association" that it would be a recognised method.

Suppose i can always email a copy of final plans to local B.C. - they are pretty good up here if your asking for advice / confirmation.

 

[Howsie]

You will struggle without skin as well. Heat leak is there for a reason.

 

[Nostrum]

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

 

[dlm4473]

Howsie - the heat exchanger IS the heat leak !

 

[Killy Bing]

Howsie - the heat exchanger IS the heat leak !

thats silly

a heat leak has to be able to act on gravity in the event of power failure and be able to disperse a certain amount of the heat that the stove can generate !!!!

unless that's a bloody big heat exchanger !!!

 

[SimonG]

Why re invent the wheel when there are a number of systems in place to do exactly what you want that are acceptable methods to building control.

Can I ask if you are an engineer op?

 

[Gray0689]

Howsie - the heat exchanger IS the heat leak !

Think about the wording HEAT-LEAK
A hex is not that

 

[dlm4473]

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.

 

[Dotty]

Think you need to get someone in before it costs you a lot of money.

 

[SimonG]

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.

Contravenes the energy eficiency part of the building regs.

Also what happens when the valve fails?

 

[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