pump on solid fuel to overcome pipe drop

[john5711]

Hi
Looking at some time connecting my solid fuel boiler up to HW cylinder, problem i have is where cylinder is the first floor drops by about 350mm
so can not get a continues rise in pipe work, attached should be a diagram i think would overcome this issue, can you see any issues with what i have drawn? if the pump was to fail it is on the return side so if water in boiler got too hot the is no restriction to the vent pipe, also the is the heat sink rad, but not sure if the pump been in that position if it failed would restrict the return to much from the heat sink rad, if i put the pump before the return do you think the pump would interfere with the return as it would be positive pressure,
Thanks
John

 

[SimonG]

What part of the country you in? Just want to make sure nowhere near me.

This is not a DIY job, it needs a competent, experienced individual to sort it.

 

[john5711]

What part of the country you in? Just want to make sure nowhere near me.

This is not a DIY job, it needs a competent, experienced individual to sort it.

I know its not a DIY job just asking a second opinion if that's the best way to overcome a drop of 350mm,

 

[SimonG]

I know its not a DIY job just asking a second opinion if that's the best way to overcome a drop of 350mm,

NO.

 

[ShaunCorbs]

Can’t have a drop or trap

 

[john5711]

so what your saying is basically the solid fuel boiler can not be connected to the cylinder because of a 350mm drop and a circulation pump wouldn't over come the problem, and the is no other way round it?

 

[SimonG]

so what your saying is basically the solid fuel boiler can not be connected to the cylinder because of a 350mm drop and a circulation pump wouldn't over come the problem, and the is no other way round it?

Not saying there isnt a way round it, just that your way isnt it.

 

[Ric2013]

Not a 'competent person', but have seen a few woodburner systems. I'm not commenting on your specific house, so take these as general comments.

I wouldn't rely on a cylinder to be the primary circulation as once the cylinder is hot, convection goes down to near zero anyway. You need 2 things: constant circulation (by gravity) AND a vent. You are correct to say the pump must not be on the heat-leak circuit. You can use separate tappings for gravity and pumped circulation at the boiler, or go down the injector tee path which would ensure you don't have the risk of the pump fighting the convection in the gravity part of the circuit.

Who's to say the cylinder will be the the main place the heat goes anyway? You could have a gravity-fed radiator which, if large enough, could be your primary circulation [edit: need to make sure this CANNOT airlock] and then you will pump everything else. If your system is designed such that the cylinder is no longer integral to the safety of the system, then there's no real reason not to have the cylinder pumped on drops.

22mm is almost certainly too small for the vent. Imagine the water in the boiler expanding to 1600x its volume and you'll understand why we like to overengineer for the worst thing that might happen. The risk with this kind of system is that gravity systems have become a niche product, and not everyone understands them now, so sometimes normal practice will not be safe.

 

[ShaunCorbs]

so what your saying is basically the solid fuel boiler can not be connected to the cylinder because of a 350mm drop and a circulation pump wouldn't over come the problem, and the is no other way round it?

Correct the flow always has to rise and return has to drop / fall back to burner can’t have a pump on it to push / get over a drop / trap as you always need flow else it’s a bomb

Other than boxing in so that the flow always rises and return drops etc no

Or move the cylinder/ thermal store

 

[john5711]

Correct the flow always has to rise and return has to drop / fall back to burner can’t have a pump on it to push / get over a drop / trap as you always need flow else it’s a bomb

Other than boxing in so that the flow always rises and return drops etc no

Or move the cylinder/ thermal store

Forgetting the pump, what would be the difference from my 350mm drop, and solid fuel boiler on ground floor with flow and return rising up to the attic running across the attic then down to a cylinder on the first floor?