Moving feed tanks OUT of loft INTO airing cupboard?

turpis · 2 Nov 2025

My house has a very typical setup: airing cupboard in bathroom with the ~~unvented~~ vented cylinder in, two tanks in the loft for the CH and HW systems.

I want to add more insulation in the loft space but the tanks are in the way. Thought about raising them up on boards but would be a right pain as it's a small space which I have to squeeze between two rafters to access, and it's a nightmare for maintenance regardless.

So I'm wondering about taking them out of the loft and moving them into the airing cupboard directly below. So I'd have the cylinder with the two tanks on shelves above. This means they'd be about 1m lower than current.

Connections to the cylinder should remain the same, will just need to route new overflow pipes through the wall (currently going under the roof tiles into the gutter)
All cold water in the house is mains-fed, all hot water is fed from an electric pump, so can't see any pressure issues there.
I'm not sure about the CH system though - does there need to be a min height between the feed tank and circulation pump / highest rad?
Any other concerns? Cheers

cross thread · 2 Nov 2025

You will loose a fair bit of hot water pressure due to a lower head

turpis · 2 Nov 2025

cross thread said:
You will loose a fair bit of hot water pressure due to a lower head

Like I say, all HW in the house comes from an electric pump

trojanhawrs · 2 Nov 2025

turpis said:
My house has a very typical setup: airing cupboard in bathroom with the unvented cylinder in, two tanks in the loft for the CH and HW systems.

Any other concerns? Cheers

This is open vented by the sounds of it!

F&E tank level 1m above highest point in heating system (normally primary circuit return on cylinder, if you have any vertical rads bear this in mind). Tank level should also be pump head / 3 minimum higher than the circulation pump (e.g. 5m head 1.7m above pump)
Cold cistern vent should have the bend back into the tank 150mm + 40mm per metre of head above the water level. Total head is measured from the bottom of the cylinder to the tank water level.

If your current hot pump is positive pressure, you may need to swap it to a universal (identified with a small pressure vessel on the pump itself) as the reduced flow might not be enough to kick the pump on in your upstairs showers.

turpis · 2 Nov 2025

Thanks very much @trojanhawrs this is just the info I needed. Could you clarify a few things?

trojanhawrs said:
Tank level should also be pump head / 3 minimum higher than the circulation pump (e.g. 5m head 1.7m above pump)

Is the pump head the distance from the pump to the lowest point of the heating system i.e. bottom of lowest rad?

trojanhawrs said:
Cold cistern vent should have the bend back into the tank 150mm + 40mm per metre of head above the water level.

You lost me here, what's the cold cistern vent - you mean the overflow on the HW feed tank? What do you mean by 'bend back into the tank'?

trojanhawrs · 2 Nov 2025

turpis said:
Is the pump head the distance from the pump to the lowest point of the heating system i.e. bottom of lowest rad?

The pump head will be labelled on the pump or in the manufacturers documentation.

turpis said:
You lost me here, what's the cold cistern vent - you mean the overflow on the HW feed tank? What do you mean by 'bend back into the tank'?

The top pipe coming out of an open vented cylinder is a vent pipe which goes straight up over the cold feed tank and bends back to drop into the tank, this is to give somewhere for the hot water to expand and air to be expelled. Normally the hot water is drawn off this same pipe at the top of the cylinder, it's illegal to put a valve on it as it could cause the tank to explode. It should also be continuously rising until it reaches the bend above the tank

turpis · 2 Nov 2025

trojanhawrs said:
The top pipe coming out of an open vented cylinder is a vent pipe which goes straight up over the cold feed tank and bends back to drop into the tank, this is to give somewhere for the hot water to expand and air to be expelled. Normally the hot water is drawn off this same pipe at the top of the cylinder, it's illegal to put a valve on it as it could cause the tank to explode. It should also be continuously rising until it reaches the bend above the tank

Ah I see, so that bend should be 150mm + 40mm/m above the feed / expansion tank level? Thanks

trojanhawrs · 2 Nov 2025

turpis said:
Ah I see, so that bend should be 150mm + 40mm/m above the feed / expansion tank level? Thanks

No. The F&E tank is for your central heating circuit. The Cold water cistern is for your hot water cylinder. The cylinder/cold water cistern MUST have a vent pipe, the F&E tank often has a shared feed and expansion pipe which again is illegal to valve.

turpis · 2 Nov 2025

trojanhawrs said:
No. The F&E tank is for your central heating circuit. The Cold water cistern is for your hot water cylinder. The cylinder/cold water cistern MUST have a vent pipe, the F&E tank often has a shared feed and expansion pipe which again is illegal to valve.

Sorry, there's a lot of similar terms that are easy to confuse for the layman - feed tank, expansion tank, header tank, cold cistern is a new one. I know the tank and vent pipe you mean though, and I don't plan on valving it & turning it into an unvented system!

trojanhawrs · 2 Nov 2025

turpis said:
Sorry, there's a lot of similar terms that are easy to confuse for the layman - feed tank, expansion tank, header tank, cold cistern is a new one. I know the tank and vent pipe you mean though, and I don't plan on valving it & turning it into an unvented system!

Yeah there's lots of different names, F&E always refers to the heating circuit tank though

Madrab · 3 Nov 2025

CWSC - Cold Water Storage Cistern - this is the large cold water container that holds the largest volume of water, usually in the loft, to supply the HW cylinder and sometimes cold water to a bathroom, it is also where the HW cylinder vent can terminate into
F&E cistern - Feed and expansion cistern for the central heating, it supplies the central heating system with top up water, allows for system water expansion and also is the location for the open vent's vent pipe to terminate into.

A cistern is a non sealed container with a lid that is removable, typically made of the same material, designed to hold liquids, usually water. A tank is usually a sealed container that can store liquids and/or gases, etc.

Feed tank/header/cold water tank etc are just other names that people use to describe these 2 items.

Hugh Jaleak · 3 Nov 2025

Insulation is only a job you're likely to do once, if you can work around the existing Cisterns I would do so, less hassle than moving them surely! You don't (shouldn't!) need to insulate underneath them as the rising warm air from below helps prevent freezing in colder weather, although both cisterns should still have adequate frost protection fitted.

Harry Bloomfield · 3 Nov 2025

turpis said:
I want to add more insulation in the loft space but the tanks are in the way. Thought about raising them up on boards but would be a right pain as it's a small space which I have to squeeze between two rafters to access, and it's a nightmare for maintenance regardless.

The purpose of it being sat on the loft floor, is to allow some heat from below, to help prevent freezing. Towards this end, no insulation should be placed under these tanks, but insulation should be on exposed pipes, and around the tanks,

denso13 · 3 Nov 2025

turpis said:
I want to add more insulation in the loft space but the tanks are in the way.

Insulate up and over the cisterns, leave underneath them clear.

turpis · 3 Nov 2025

It's a good suggestion to insulate over them and I would be tempted but they're in such an awkward position - right at the point the rear extension joins to the house. To get at them for maintenance / repairs I've got to squeeze between about a 300mm space between two rafters, and even then one cistern is in the way of the other so it's nearly impossible to get to the one at the back without treading on the pipes for the one at the front!

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Moving feed tanks OUT of loft INTO airing cupboard?

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