Drain back system on back boiler

[Doodlebug]

Hi,

 

I had no idea which section this should go in so I put it here.

 

Basically I am looking into solar water heating, and was looking at how the systems sometimes drain back down, emptying the pipes to prevent overheating.

 

Then I was looking at how I might tie both the stove and the solar heating into one system, and then I started thinking about how I would prevent the back boiler overheating.

 

Then it occurred to me that I could make a drain back system, in which water is pumped into the bottom of the back boiler, which then flows up and out the top, through the water tank and back again. When the hot water has reached its temperature the pump could switch off, and the boiler could then drain itself.

 

Is that a system already in use or am I missing something?

 

I cant do gravity fed stuff because the stove is too high.

 

Thanks!

[Taslim]

I think that is a potentualy dangerous idea. When the temperature drops & the pump kicks in again water could be introduced to a wery hot back boiler. Apart from the thermal stress on the metalwork i think you could risk fast boiling/steam generation.

 

Hopefully MtB will turn up & put us right.

 

taslim.

[Grace and Favour]

Hi,

 

I had no idea which section this should go in so I put it here.

 

Basically I am looking into solar water heating, and was looking at how the systems sometimes drain back down, emptying the pipes to prevent overheating.

 

Then I was looking at how I might tie both the stove and the solar heating into one system, and then I started thinking about how I would prevent the back boiler overheating.

 

Then it occurred to me that I could make a drain back system, in which water is pumped into the bottom of the back boiler, which then flows up and out the top, through the water tank and back again. When the hot water has reached its temperature the pump could switch off, and the boiler could then drain itself.

 

Is that a system already in use or am I missing something?

 

I cant do gravity fed stuff because the stove is too high.

 

Thanks!

IF you want to heat your domestic water with output from your solar - surely you should just get a calorifier with an extra circuit in it, and then fir a valve (temperature controlled?) on the solar circuit so you don't heat that up when the sun ain't shining.........

[MtB]

I think that is a potentualy dangerous idea. When the temperature drops & the pump kicks in again water could be introduced to a wery hot back boiler. Apart from the thermal stress on the metalwork i think you could risk fast boiling/steam generation.

 

Hopefully MtB will turn up & put us right.

 

taslim.

 

I quite agree. This and a million other potential problems.

 

I know enough about systems with uncontrolled heat sources to realise how little expertise I have, and how things can go badly wrong in a system designed by someone without the necessary expertise. One uncontrolled heat source is difficult enough, two is four times as tricky!

 

Consequently I can't offer any solid, reliable advice (other than be very careful) which is why I didn't contribute when I first saw the thread.

 

 

MtB

 

 

Edit to add: The peeps who really know about this stuff in depth, hang about on the forum at www.navitron.org.uk

Edited May 22, 2013 by Mike the Boilerman

[Doodlebug]

Thank you for the advice. I see what you mean. As the water flows back into an empty boiler it will create huge amounts of steam. I hadn't really thought about that.

 

I will keep the two systems separate as well, but I think maybe I should just have the back boiler heating radiators and use gas for water. Its not like it uses a huge amount of gas.

 

Thanks again.