Hot water flow and return

[johno12345]

Hi,

We are refurbishing at work and we plan to install a large electric megaflow cylinder to feed some showers and taps which are close by. Additionally, we are going to feed some distant basins and sinks. I want a flow and return installed on the long run.

Is there any information about the place regarding these systems? I like to know how things work before we have people in to quote

Thanks

 

[Breesey]

Do you you mean a secondary flow loop?

 

[johno12345]

I think so, that is probably why I cant find any info I was thinking that if there was a pump in the loop at the cylinder, could it cause suction on the taps and draw air in when the taps were opened? Presumably there is a way of preventing this?

Thanks

 

[Breesey]

Alot of unvented cylinders are available with a secondary return boss. You would need a brass pump for this application, these are fairly expensive.

 

[Balenza]

johno wrote

Is there any information about the place regarding these systems?

Have a read through the link below and then feel free to ask any questions.
And NO, they don't draw air in when the taps are opened.

//www.diynot.com/forums/viewtopic.php?t=101851&postdays=0&postorder=asc&start=0

 

[johno12345]

Hi,

That was informative, I assume we dont need a mixing valve as that is done at the point of use.

I was planning on a 300l heatrae sadia with 3 immersions which can have the return teed into it. Are heatrae sadia the best or would you recommend another make?

Is the return loop done in 15mm while the primary feed is done in 22mm?

Will we need an additional expansion vessel as there will be some 50M of 22mm and then the return loop?

I was going to have the pump on a timer so it only ran when that building was open, I hadn't thought of a pipestat to switch the pump in and out, is this just a good idea or a requirement?

When we say that the pumps are expensinve, are we talking more than about £300?

Lastly, one of our other plumbers told me that it was pointless lagging hot water pipes, loop or otherwise as virtually no heat would be lost anyway, smells fishy to me

They are coming tomorrow to look at the job so at least now I have an idea of what is going on

Thanks