Pump assistance for thermosyphon?

[MattB]

I hope someone can help, as my thermosyphon powered hot water tank has been moved, it takes ages to heat up and the boiler keeps cycling. I can only assume that the narrow pipes and long horizontal run have stopped this working well. I do not want to disturb the pipework much, so adding a pump seems like a good idea. My worry is that the head on a normal circulation pump will end up forcing water up and out of the vent pipe.
Is there a recognised way of giving a thermosyphon a bit of a helping hand?
Cheers in advance.

 

[ShaunCorbs]

You mean gravity hot water ?

Why was it moved ?

 

[rpm]

Is this with a back boiler?

 

[MattB]

Yes, gravity fed from a conventional boiler with a pumped circuit for the radiators and gravity for the hot water. It will be a massive job to make the hot water run off the pumped circuit, so I wanted a simple solution. The tank was moved from the bathroom up to the loft and the plumber only used 22mm pipes and there is a long level run across the loft to the tank. If I dud go with the pumped circuit, can I simply cap off the gravity ports on the boiler?

 

[ShaunCorbs]

Well he’s done wrong as he needs to bring it upto regs and energy efficiency eg fully pumped s plan etc

Also gravity circuits can’t be level need to rise

 

[MattB]

This was done before we moved in ☹️, so should it be pumped then?

 

[ShaunCorbs]

Correct

 

[MattB]

Right, thanks!

 

[John.g]

Well he’s done wrong as he needs to bring it upto regs and energy efficiency eg fully pumped s plan etc

Also gravity circuits can’t be level need to rise

Well he’s done wrong as he needs to bring it upto regs and energy efficiency eg fully pumped s plan etc

Also gravity circuits can’t be level need to rise

Are (were) these combined systems only installed on gas fired boilers?, apart obviously on solid fuel boilers. Assuming a properly installed cylinder with vertical pipe runs what approx is the cycling time assuming the cylinder is nearing full temperature? Oil fired boilers like my own cycle very frequently under the above conditions with a all pumped system.

 

[MattB]

This is a gas fired boiler in my case. The cycling is much more than when pumping the radiators.

 

[John.g]

This is a gas fired boiler in my case. The cycling is much more than when pumping the radiators.

Thanks, the cycling would be far greater on oil firing (with gravity cylinder circuit) as oil fired boilers don't modulate, I was just wondering if anyone had seen one plumbed this way despite the above.