Primatic cylinder - options

[Servotech]

I did take it that the 10m run that you mentioned is mainly horizontal pipework and if so this will be the reason why it's slow to heat up.

Two pumps not a problem.
I would put the pump on the primary flow and set it to the lowest speed.
Fit an air separator onto the expansion pipe and put the cold feed into it (this should resolve any pumping over issues)
For a really cheap wire up/contol you could plug the pump/cylinder stat set up into a plugged in time switch that's set to come on the same time as the boiler.
I've drawn a diagram of it and uploaded into my pictures so you can take a look at.
I can't see any problem with the system, although you won't find it in any plumbing manual - but for your specific needs it's just the job.

 

[bash1978]

yes most of the piping is horizontal. I have had a look at the diagram, just a few points of clarification.

First, can I add the pump on the flow near to the boiler instead (does it matter where the pump is fitted as long as it is on the HW flow ?

Second, not sure how the air separator works, can you explain what its there for, do I have to have it, any other options ?

Third, I assume the valves on the diagram are the normal pump valves and nothing else ?

Finally, my pump on the CH is on the return flow would that make any difference to what you have suggested in terms of flow problems ?

Thanks

 

[bash1978]

Also added some diagrams myself of what the current system looks like and what I think you are suggesting, plesae can you have a look and let me know if that is what you have suggested.

Just confirm where on the HW flow I can put the pump plz, its easier to put near boiler as I have some room.

 

[bash1978]

Current Setup
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Proposed fully pumped Setup
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[Servotech]

Yes, near the boiler would be fine and it means you can easily wire it so that the new h/w circulation pump will automatically come at the same time that the boiler does.
One thing I realised that I had overlooked is that no valves are permitted on a pipe that is the main boiler expansion pipe!
(The valves are just normal pump valves for servicing the pump).
No reason though why you cannot take the boiler expansion tee from the primary return (no valves on this) on the cylinder though, then just fit a air vent on the primary flow slightly above the tee leading to the flow connection on the cylinder.
I would still fit the air separator (which allows you to connect the cold feed to the same pipe as the expansion without the risk of pumping over).

With these extra little modifications It looks good.
I'll do a modified diagram later on today

 

[Servotech]

I've just put two revised diagrams in my images (I don't seem to be able to insert them into my posts).
I've been thinking about this today and I think if you can fit the pump on the primary return instead of the primary flow (near the boiler) things will work out much better.
Because you are now fitting the pump closer to the boiler and therefore increasing the head of water above the pump I think that it's worth a try without the air separator.
If it does pump over you can then always fit the air separator,but give it a go without first.
Please do let me know which system you decide on.
And how the fit goes (when you do it).

 

[bash1978]

OK servotech, I have had a look at the diagrams, and am a bit confused.

I would prefer option A, as I think I can fit the pump near the boiler on the HW return from cylinder and link it up. But you seem to be suggesting from your arrows that the flow of water is the other way around the system i.e. normal return is now flow and flow is now return, do you mean that ?

Which way is the pump going to pump, I would have thought its towards the boiler ?

 

[Servotech]

That's good news then that you have room to fit the pump on the return near the boiler, it certainly makes things easier in the airing cupboard.

The pump is said to be more efficient pushing water (positive) than pulling (negative) and ch systems today are mainly under positive force.
Without thinking I automatically drew the direction of flow > putting the circuit under positive force.
However, I get what you are saying that the new circuit is moving in reverse circulation.
I don't think it really matters which way round the pump goes in a forced circulation circuit of this type.
If you are more happy with the pump pumping into the boiler < then so am I.
So we'll say fit the pump pumping towards the boiler putting the circuit under negative force as the final revision.

A couple more points.

I've noticed that you've drawn an "anti gravity valve" in the flow of the heating circuit you might like to consider removing this whilst the system is drained down because the things usually cause trouble sooner or later.

Just a reminder when you drain the primatic cylinder you need to drain the domestic side of the cylinder (either via the drain tap on the cold feed or syphoned through the top connection on the cylinder) as well as draining the heating (you probally already knew this but I've known even proffesionals make this mistake)

Good luck, and when it's ll working, please post up again, I'd very much like to know how the system is performing.
Servotech

 

[JohnD]

bash1978

I can't reply to your message because in "Message Settings" you have not enabled
" Who can send you messages?
All Registered Users"

anyway my experiences are on

//www.diynot.com/forums/viewtopic.php?p=1229459#1229459

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