Gravity feed (only) hot water system

[AquaHydroChem]

Hi there
Is it possible for me to have a boiler/ heat exchange that would heat the water and send it to a storage tank higher up then the heat exchange its self?
I mean I want the water to circulate from the heat exchange to the water tank and back round again on a constant loop with out a water pump

Thanks

 

[Dan Robinson]

No.

 

[Dan Robinson]

Assuming a domestic property that is.


Why?

 

[Nozzle]

Natural circulation, the hot water will go up and be replaced by cooler water going down. It works in principle, it can be made to work practically, but I doubt a domestic boiler would like it. To set up natural circulation and carry on taking all the heat away it is driven by difference in coolant density, in turn that is difference in temperature. The water inside the heat exchanger might not still be liquid at the temperature required... this also still works, but is not going to be pretty! (banging, gurgling, errosion and eventual destruction of the heat exchanger.

Nozzle

 

[bernardgreen]

Not with a modern boiler which needs a forced ( pumped ) circulation through it's heat exchanger.

Old and ancient boilers with heat exchangers built with vertical tubes, cold water entry at the bottom amd hot water take off at the top did work in a gravity system. They were large, tall and in-efficient.

 

[AdvanceHelpline]

You would need to pump into the plate heat exchanger and out of it to your hot water tank for it to work

 

[Mottie]

We used to have a gravity hot water system and pumped heating. The hot water tank was in the airing cupboard next to the boiler (which was in the kitchen) and the tank was higher than the boiler. Totally useless as an airing cupboard as heat doesn't go down so I dropped the tank and converted the system to a fully pumped one. Every time British Gas came round to fix it, they kept telling me it was unsafe as I needed so many open vents in the kitchen it was permanently freezing. I had a new boiler fitted 6 months later and located that in the loft.

 

[JohnD]

Do you mean a gas boiler?

Or are you thinking of, say, a woodburner or multifuel?

 

[AquaHydroChem]

No this would be a home job; radiator on the back of the log burner as the heat exchange
But I get the message, very complicated so most probably need it pumping round

 

[JohnD]

you can have gravity flow to heat a cylinder above a logburner or multifuel. I've had one, as do relations still. To heat radiators though, takes quite a big stove. You could do one in the bathroom, say, and bedroom, but you have to burn an awful lot of wood to get enough heat. If you have one big enough to heat several radiators I think you will need a pumped system.

The other responders assumed you meant gas.

There are people qualified in the safe design and installation of these stoves.

 

[Agile]

You did not make it clear.

In fact what you propose will work fairly well as long as you keep the pipework short and directed towards its termination.

But to get any useful circulation you will need at least 22 mm and probably 28 mm. Certainly not 15 mm which is used for pumped rad connections.

 

[AquaHydroChem]

No the radiator is the heat exchange that is being heated at the moment
To be honest I plumbed it all up to my 12v shurflow pump before and the fire and rad are hot but I will try it a bit later on

No its all been on 13mm, so what your saying is for gravery feed system to work it needs large bore pipes and be in a stright line with no bends and not a lot of graverty or distance from tank to heater for it to work?

 

[Mottie]

If you mean me,

You did not make it clear.

In fact what you propose will work fairly well as long as you keep the pipework short and directed towards its termination.

But to get any useful circulation you will need at least 22 mm and probably 28 mm. Certainly not 15 mm which is used for pumped rad connections.

Yes, now you mention it, our one had massive pipes (and a short run) so must have been 28mm. It was nearly 25 years ago now but I seem to remember that the bathroom radiator would sometimes get hot even with the heating off in the summer.

I digress but I can remember when some cars had a gravity cooling system and the top (outlet) radiator hose practically went straight up from the centre of the cylinder head to the rad. For that you needed a tall radiator and a high bonnet. It was the fitting of water pumps that allowed manufacturers to lower the bonnet line on cars.

 

[Dan Robinson]

No this would be a home job; radiator on the back of the log burner as the heat exchange
But I get the message, very complicated so most probably need it pumping round

Perhaps next time you can give us a reasonable amount of information?

 

[AquaHydroChem]

Perhaps next time you can give us a reasonable amount of information?

what do you need to know?