Woodburning stove and gravity hot water

[Andy]

Hi,

I am new to this forum and this is my first post.
I am looking for some advice regarding the fitting of a vented indirect hot water cylinder to my boiler stove.
Unfortunately I was sold a cylinder that I was told was suitable for a gravity fed system when it wasn't loud bangs later and a leaking cylinder.
I now plan to get a cylinder with a 28mm coil/heat exchanger and 28mm fittings
The system comprises a multifuel boiler stove with 4 tappings off the boiler.
Two diagonal ones feed a series of rads using 22mm & 15mm copper pipe with a Danfoss pump.
The other pair of tappings comprise the gravity fed ho****er circuit with a cold feed to the bottom in 15mm copper and a 22mm vent to the top.
There is a 2.5 metre head of water from the header tank for this circuit - the dwelling is single storey cottage.
The hot water cylinder is higher up than the stove but obviously on the ground floor.
What I want know is this a reasonable/safe system?
There will be high and low level stats to turn off/turn on the pump.

Thanks for any advice

Andy

 

[SimonG]

What happens when the pump fails or no electric, how you going to dissipate the heat?

 

[Andy]

What happens when the pump fails or no electric, how you going to dissipate the heat?

Hi SimonG,

I forgot to add that there will be a heat leak radiator fitted part way up the wall - so as to be higher than the stove and so enable gravity flow.
This will be always on and set so that it cannot be turned off.
Andy

 

[Best]

As long as the 28mm primaries are very carefully installed to allow gravity flow & you have heat leak, it should be safe. I would like the feed pipe in 22mm.

I should add that the pipes should be well protected from freezing, especially in attic.

 

[Andy]

Hi Best,

Thanks for your reply. I will change the feed to 22mm, I was beginning to think that 15mm was perhaps too small.
The primaries are properly installed. Will be getting a cylinder made up with 28mm coil too.
Hopefully things will be OK then.

Andy

 

[AWheating]

22mm to the heat leak rad (last 30mm in 15)connected top and bottom with lockshields, normally open zone valve operated by a cylinder stat, temp relief valve on the cylinder with discharge pipework as per part g of the building regs.

 

[Gray0689]

22mm to the heat leak rad (last 30mm in 15)connected top and bottom with lockshields, normally open zone valve operated by a cylinder stat, temp relief valve on the cylinder with discharge pipework as per part g of the building regs.

Don't see the point of 22mm to heat leak rad your reducing down to 15mm so no point mate imo

 

[AWheating]

Don't see the point of 22mm to heat leak rad your reducing down to 15mm so no point mate imo

is whats specified by hetas. i guess its more important the further away the rad. If you can get a rad with 3/4 tapping then even better.

best to fit to hetas spec if building control is signing off.

 

[Gray0689]

Well if its what they spec then better to do it
No hetas regulations over here

 

[AWheating]

Well if its what they spec then better to do it
No hetas regulations over here

is there no body that regulates solid fuel?

 

[Gray0689]

Just building control bot they don't have a clue to be honest as long as ventilation is in that's it

 

[Nostrum]

22mm is to reduce frictional loss for gravity circulation rather than heat loading, I thought it was last 150mm in 15mm but could be wrong, been a while since I've looked at the books!

 

[AWheating]

22mm is to reduce frictional loss for gravity circulation rather than heat loading, I thought it was last 150mm in 15mm but could be wrong, been a while since I've looked at the books!

you may be right Sam, i cant be bothered to check tho lol. 🙂