Y plan component placement.

Steve shuff · 16 Oct 2021

Hello all.

Background...
I am a 56 year old guy working on a 400 year old property which I have recently inherited from an Uncle.
Many years ago I trained as an electrician and also have done many plumbing jobs including full CH systems.
Currently I am installing a Y plan system into my property , the boiler will be oil fired.
The boiler will be situated in a ground floor room and also in this room approx 3 metres away will be the indirect cylinder. A loft is above this room . The rest of the house has a ground floor on the same level as the boiler room (ground floor has radiators fitted along with the upstairs ).. The main flow and return for the radiators enter the loft above the boiler and cylinder room.
MY QUESTION..
Is it ok to fit the pump and motorised valve in the loft space above what will be the airing cupboard ?

The loft in is a warm loft (insulated rafter space) as the water tanks are fitted there so it is highly unlikely it will freeze up there.
Any advice would be most welcome, thanks..

kidgreen61 · 16 Oct 2021

Can't see that being a problem at all, as long as the access is good for maintenance/repair.
Don't forget to make the return from the cylinder the last tee before boiler.

fixitflav · 16 Oct 2021

Steve shuff said:
Hello all.

Background...
I am a 56 year old guy working on a 400 year old property which I have recently inherited from an Uncle.
Many years ago I trained as an electrician and also have done many plumbing jobs including full CH systems.
Currently I am installing a Y plan system into my property , the boiler will be oil fired.
The boiler will be situated in a ground floor room and also in this room approx 3 metres away will be the indirect cylinder. A loft is above this room . The rest of the house has a ground floor on the same level as the boiler room (ground floor has radiators fitted along with the upstairs ).. The main flow and return for the radiators enter the loft above the boiler and cylinder room.
MY QUESTION..
Is it ok to fit the pump and motorised valve in the loft space above what will be the airing cupboard ?

The loft in is a warm loft (insulated rafter space) as the water tanks are fitted there so it is highly unlikely it will freeze up there.
Any advice would be most welcome, thanks..

Are you thinking of having a F/E tank, or an expansion vessel? In either case, there needs to be enough pressure at the pump suction to give the NPSHR. Should be OK, but worth a check.

Steve shuff · 16 Oct 2021

Thanks for the help guys.

It will be an F/E Tank about one meter above the upstairs radiators.
The boiler will be opposite the cylinder so the pipework will go from those up into the loft where the pump and mot. Valve will be.
It's just so much neater doing it that way and plenty of room for access.
The property gets its water from a spring (no mains)
Which is fed to an underground reservoir then pumped into the header on a float switch call.

It will be interesting filling the CH system !,

Thanks again.

fixitflav · 16 Oct 2021

Steve shuff said:
It will be an F/E Tank about one meter above the upstairs radiators.

That doesn't sound right. Apart from NPSHR, the F/E tank must be above the highest point of the system.

Steve shuff · 16 Oct 2021

Hello and thanks.
The F/E tank will be the highest part of the system.
Sorry, I possibly didn't make that clear earlier.

fixitflav · 16 Oct 2021

Steve shuff said:
Hello and thanks.
The F/E tank will be the highest part of the system.
Sorry, I possibly didn't make that clear earlier.

OK, but sounds like the top of the upstairs rad is quite close to the ceiling, if 1 meter above that is higher than the pump in the loft.
I have a Grundfos leaflet which says "The minimum pump inlet pressure at 90°C should be 1.5 m to avoid cavitation and to ensure quiet running"

Steve shuff · 16 Oct 2021

Sounds good,
I can elevate the feed expansion tank so it is approx 1.3 metre above the pump.
This will place the tank approx 1.2 metres above the top of highest radiator . The pump will sit at approx 40cm (at same elevation with M. Valve) below top of highest radiator.
2 Metres below this on the ground floor will be the boiler and cylinder which will be at same elevation as all downstairs radiators.
Clear as mud !!
Ps. I moved from Wolstanton SOT to South Shropshire Hills !

fixitflav · 16 Oct 2021

Steve shuff said:
I can elevate the feed expansion tank so it is approx 1.3 metre above the pump.
This will place the tank approx 1.2 metres above the top of highest radiator . The pump will sit at approx 40cm (at same elevation with M. Valve) below top of highest radiator.

Can't quite make your levels add up, but no matter, 1.3m above the pump is the important one, which should be OK. Grundfos's 1.5m no doubt has a little safety, and temperature is unlikely to be 90°C.

Steve shuff said:
Ps. I moved from Wolstanton SOT to South Shropshire Hills !

I'm sure you won't regret it

bernardgreen · 16 Oct 2021

Steve shuff said:
The boiler will be situated in a ground floor room and also in this room approx 3 metres away will be the indirect cylinder.

If boiler and and cylinder are in the same room then why are you putting the pump in the loft above that room ?. I would think the pump and valve could be close to the boiler. with feed to and return from the cylinder not going into the loft. The only reason I see for taking them through the loft would be the need to run these pipes across the room.

Steve shuff · 16 Oct 2021

That is correct, Boiler and cylinder are opposite each other at a distance of approx 3 metres, so the pipework will go up into the loft for connections.

Steve shuff · 18 Oct 2021

Having had more of a think over the weekend I am wondering if a better placement for the pump would be next to the boiler, and in which case on the flow or return side ?
Thanks for any advice .

fixitflav · 18 Oct 2021

Steve shuff said:
Having had more of a think over the weekend I am wondering if a better placement for the pump would be next to the boiler, and in which case on the flow or return side ?
Thanks for any advice .

I think it's more common to have pump on the flow, but either is OK AFAIK. Either gives better pressure at the pump suction. On return means the pump runs at lower temperature, which might mean improved life, but hardly worth worrying about.

If on the flow, circuit should be boiler - open vent - cold feed - pump. That might mean fairly long pipe runs from the F/E tank.

On the return, open vent - cold feed - pump - boiler. You might be able to find a common return pipe run remote from the boiler to plumb in the open vent and cold feed, but it depends on the house layout.

You also need to decide where to put the diverter valve.

Steve shuff · 18 Oct 2021

Sounds like the return near the boiler may be the best place for the pump and then the diverter valve would go in the loft ( I take it diverter is same as motorised valve ).

The feed and expansion can go near the motorised valve , How far apart do the feed and expansion "T" have to be ? or does the feed need to be near the boiler ?

The house is in two sections , Laundry section has a loft above it and in the laundry room will be the boiler and opposite will be the cylinder with a doorway between into the bathroom (thats why the pipes from boiler and cylinder go straight up into the loft .
The main radiator circuit enters this loft (approx 3m x 4m in size) so it made sense to put the motorised valve and pump in the loft .
However the F/E tank is only about 1.2m above the pump so to gain a bit more head I thought put the pump on the boiler return in the downstairs .

The living part of the house has ground floor with radiators at same height as the boiler and the upstairs radiator tops will be about 1 m below the F/E tank .

fixitflav · 18 Oct 2021

Steve shuff said:
I take it diverter is same as motorised valve

That's right. If it's Y-plan the Honeywell valve is V4073 mid-position valve. I don't think there's any significant advantage of Y-plan over W-plan, with either/or valve V4044, and hot water preference. Only the actuator is different, the valve is simpler and cheaper (I assume) and likely to be more reliable. Also if you go for weather compensation, where the flow temperature is reduced depending on outside temperature, it has to be either/or, with the boiler going to normal control-stat setting during a HW cycle.

Steve shuff said:
How far apart do the feed and expansion "T" have to be ? or does the feed need to be near the boiler ?

Do you mean the open vent and cold feed? Not more than 150mm apart. The cold feed can be 15mm, and should come up into the pipe from below, to reduce convection warming the F/E tank and encouraging growth. They can be remote from the boiler and pump.

Steve shuff said:
However the F/E tank is only about 1.2m above the pump so to gain a bit more head I thought put the pump on the boiler return in the downstairs.

OK, but does that mean the pump has to be on the return?

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Y plan component placement.

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