Expansion Tanks in sealed system

[jddevel]

What is the ideal location for an expansion tank in a sealed system and is it best off the flow or return to boiler.😕

 

[Puddle]

On the return and as near to the boiler as possible if pump is in boiler as pump on return on system boilers and combi's
Or if pump is external ie ,in the airing cupboard,the vessel should be fitted as near as possible on the inlet side of the central heating pump
The pressure release valve should a be as close the the boiler as possible on the flow side

 

[migoplumber]

like puddle says.

 

[jddevel]

Thanks Puddle. Now I`ll expand ( excuse the pun).
Due to a catalogue of errors based on a local so called plumbers advice I`ve ended up with a Grant Vortrex 15/26 kw system boiler. ( I started with a non system boiler -same size, was then told it was inadequate although our calculated heat loss was only 12kw max. as it would not run the ACV 300SLE heat store properly. So a 58/70KW was ordered. ON arrival of this HUGE thing and the "disappearance" of the first plumber two others were asked to quote they visited but didnt do so and two others I`m still waiting to see!!!!!! SO I`m dealing with as much of it myself until someone "turns" up.
Checking with ACV and Grants it turns out the original boiler was quite sufficient but then sods law instead of delivering a non-system you`ve guessed it a system boiler has arrived.
My intention is therefore to add a further 35 ltr expansion tank on the return to boiler to supplement the 12 ltr tank in the boiler. As the system boiler has provision for pressurizing and safety valve etc this should be a simple task.
Now further advice needed. The boiler is to supply the following:-
First circuit The underfloor heating- two manifolds (18 circuits) 160 ltrs

Second Circuit Four towel radiators and a standard radiator (2600btus)
Third Circuit The ACV 300 SLE
The boiler has its own pump (as stated system boiler) and I would like to control all three circuits separately. My leaning is to a Y plan with two port valve to the ACV and a three port to the towel rails/radiator on one port and the underfloor on the other thus giving me seasonal control. Is this possible or would a S plan be bettetr. What conflict will another pump creat or should I just upgrade the system pump as I fear it will not be adequate to run all thats required 1590 mtrs 16mm under floor the Heatstore and whilst small the towel radiators.
Sorry this is a bit long but advice please.

 

[Plucky]

Thanks Puddle. Now I`ll expand ( excuse the pun).
Due to a catalogue of errors based on a local so called plumbers advice I`ve ended up with a Grant Vortrex 15/26 kw system boiler. ( I started with a non system boiler -same size, was then told it was inadequate although our calculated heat loss was only 12kw max. as it would not run the ACV 300SLE heat store properly. So a 58/70KW was ordered. ON arrival of this HUGE thing and the "disappearance" of the first plumber two others were asked to quote they visited but didnt do so and two others I`m still waiting to see!!!!!! SO I`m dealing with as much of it myself until someone "turns" up.
Checking with ACV and Grants it turns out the original boiler was quite sufficient but then sods law instead of delivering a non-system you`ve guessed it a system boiler has arrived.
My intention is therefore to add a further 35 ltr expansion tank on the return to boiler to supplement the 12 ltr tank in the boiler. As the system boiler has provision for pressurizing and safety valve etc this should be a simple task.
Now further advice needed. The boiler is to supply the following:-
First circuit The underfloor heating- two manifolds (18 circuits) 160 ltrs

Second Circuit Four towel radiators and a standard radiator (2600btus)
Third Circuit The ACV 300 SLE
The boiler has its own pump (as stated system boiler) and I would like to control all three circuits separately. My leaning is to a Y plan with two port valve to the ACV and a three port to the towel rails/radiator on one port and the underfloor on the other thus giving me seasonal control. Is this possible or would a S plan be bettetr. What conflict will another pump creat or should I just upgrade the system pump as I fear it will not be adequate to run all thats required 1590 mtrs 16mm under floor the Heatstore and whilst small the towel radiators.
Sorry this is a bit long but advice please.

Is this the Smart ACV tank which is effectivly a buffer tank? The tank in tank designed job with unvented cylinder built in? Secondary coil for solar connection? If so then great choice first of all.

Does you underfloor heating manifold have its own pump?

I would personally use 2 port valves to take care of the situation.
2x 2 ports to your manifolds,
1x 2 port to your ACV
1x 2 port to your rads/towelrads

You would have to check out the size of the pump inside the boiler. I think you'd be suprised that the system doesnt actuallt demand as much as you think.

If it were me and i've gone through the trouble you have been through so far I would get the boiler swapped again. Then you can just stick a pump onto a circuit for your ACV and another pump to feed your Manifolds and Rads etc.

 

[jddevel]

Yes it is the tank within a tank but no secondary coil for solar. It was a matter of choice. I`m afraid I`m not a great lover of solar panels. I dont loke holes in roofs and there is no where else viable.
Regarding undefloor heating no pump as yet. I intend installing one which is why I thought a three port motorized valve could operate the towel rads and underfloor.

 

[Plucky]

Ok, lets start from basics what underfloor heating set up do you have? You really need manifold with pump, blending valve to keep to temp down to approc 45 degrees. its no good sticking 75 degrees through underfloor heating.

 

[jddevel]

Thanks Plucky.
Uponor two manifold supplying under floor up (8 zone) and down (10 zone)
It is intended to fit its own pump prior to three port temperature mixing valve.
So for the underfloor heating could it be a pump to three port valve one port to mixing valve for underfloor and one port to towel rads?

 

[Plucky]

OK I see. Its a real shame you have got a system boiler.

You could have come off the boiler wikth your flow, a pump to take care of 2 manifolds and the rads and a seperate pump for the ACV. Zone valves to each. I believe each UFH manifold will need its own electric blending valve to keep temps down.

-You could look af upgrading the pump inside the boiler, have to check sizing

-You could remove and bypass pump in the boiler, but pointless paying the extra for the systems boiler

Your ACV tank is it one of the basic kinds with just a flow and return connection from the boiler. You can get them with heating inputs and outputs so to speak. So you would take the Flow and return form the boiler into the tank. And then out of the tank you can take Flow and Returns to your manifolds etc ---->SmartLine SLME | ACV UK

 

[jddevel]

Plucky- Just reread your addition about the two port valves. I`ve come to the conclusion that I cant be bothered to wait for the boiler to be changed again as its holding up other jobs and I want to be in by Xmas. Two port valves it will be. The two pumps in series as asked in earlier post will they cause conflict as they both use the same primary water supply? or should I ensure they are both the same flow rate to balance?

 

[Plucky]

I wouldnt advise two pumps in series, better to have them in parralel. I would look at upping the size of pump in boiler. I have done this before aslong as new pump has correct sized centres. Or do away with pump in boiler and fot auxillary pumps.

Shame you havent got manifolds with built in shunt pumps/blending valves as you wouldnt have this problem.

 

[jddevel]

Note your comment about the blending valves. The Uponor designed system has only allowed for one blending valve immediate after a two port valve from boiler from there to a pump and tee`d to the two manifolds.

Are you saying just up size of boiler pump if possible and then just have the one pump- which makes sense? Reference comment about pumps in parallel with one in the boiler might be difficult but I wont let it beat me!!!!