A question for the Plumbers

[roofer]

I have a semi gravity system in a Bungalow. The Loft is being converted, and I don't want a tank above ground floor ceiling level.

Plan is to put cold water on mains ( Currently from cistern 50 gallon) and put a 30 gallon tank just above the cylinder in the airing cupboard, then using a negative pressure pump for hot water. (2 baths, 2 showers, 1 of each in loft)

Lunatic or doable?

I should add the heating vent/ supply tank will go into roof space due to minimal size.

Edited by roofer on Wednesday 23 July 15:26

[Sir Bagalot]

I would be going for a Megaflow

[Trevor450]

Don't go down the pump route. They are noisy and we have had a bit of a nightmare with it pulsing, despite it being correctly installed.

I would have gone unvented but our wood burner is plumbed into the hot water and that is a big no with an unvented tank. I am going to get our vented system swapped for a thermal store cylinder when funds allow due to the noise caused by the pump and those are fine with a stove but they are a fortune compared to a standard unvented cylinder.

[roofer]

Sir Bagalot said:

I would be going for a Megaflow

Mega bucks too. The 'boiler' is a gas Aga, and all of the system is tickety. Lowering the tank = a bit of pipe and a tank/pump. Aware of noise issues re pumps, but I suspect a quality pump and good mounting will alleviate this somewhat.

[andy43]

Secondhand unvented cylinder would be easiest/cheapest.
Get one with all the control/safety gear still with it and it'd be cheaper than a decent pump.
£150-200 should do it.

[Trevor450]

Similar situation to mine then - fitting an AGA to an unvented is also a no, I think. Personally, if the cupboard where the tank is has a concrete floor, fit this in there rather than up in the loft as concrete supresses the sound. Our airing cupboard has stud walls and timber floor. I have reduced the noise by placing the pump on a special closed cell foam mat which has helped no end.

[roofer]

andy43 said:

Secondhand unvented cylinder would be easiest/cheapest.
Get one with all the control/safety gear still with it and it'd be cheaper than a decent pump.
£150-200 should do it.

Also needs certifying no ?

[Neil - YVM]

roofer said:

I have a semi gravity system in a Bungalow. The Loft is being converted, and I don't want a tank above ground floor ceiling level.

Plan is to put cold water on mains ( Currently from cistern 50 gallon) and put a 30 gallon tank just above the cylinder in the airing cupboard, then using a negative pressure pump for hot water. (2 baths, 2 showers, 1 of each in loft)

Lunatic or doable?

I should add the heating vent/ supply tank will go into roof space due to minimal size.

Edited by roofer on Wednesday 23 July 15:26

That should work. Though you may have issues with the showers as they will be supplied with different pressure hot and cold? Might be better to pump both hot and cold.

For that number of baths / showers you will probably want a 3 or 4 bar pump, and therefore will need a min 100 gallon cold water tank or 2 50's manifolded together.
Also consider if the existing hot cylinder has sufficient capacity to feed / recover 2 showers / baths.

[roofer]

Neil - YVM said:

That should work. Though you may have issues with the showers as they will be supplied with different pressure hot and cold? Might be better to pump both hot and cold.

For that number of baths / showers you will probably want a 3 or 4 bar pump, and therefore will need a min 100 gallon cold water tank or 2 50's manifolded together.
Also consider if the existing hot cylinder has sufficient capacity to feed / recover 2 showers / baths.

I could run mains to the pump for cold, and negate need for 100 gallon ? Understand the equal pressure thing. Don't have space for 2 50 gallon tanks.

[TA14]

roofer said:

I could run mains to the pump for cold.

I don't think that you're allowed to pump the mains.

[roofer]

TA14 said:

I don't think that you're allowed to pump the mains.

I think you're right, I'll run the pipe through a dummy tank ...;-)

[TA14]

roofer said:

I don't want a tank above ground floor ceiling level.

How about small tanks next to the eaves and linked together? That area has the capacity to carry the highest load and is rarely used for anything.

[Neil - YVM]

roofer said:

I could run mains to the pump for cold, and negate need for 100 gallon ? Understand the equal pressure thing. Don't have space for 2 50 gallon tanks.

I assume your joking about pumping the mains?

Try measuring the incoming mains pressure, if close to 3 - 4 bar then ok to connect cold to shower and only pump hot. If higher then maybe a pressure reducing valve?

I still think you will need a larger cold water tank than 50 gallon even for a 3/4 bar single. As some else suggested, have you the space to fit a coffin tank or two in the eves?

[roofer]

Neil - YVM said:

roofer said:

I could run mains to the pump for cold, and negate need for 100 gallon ? Understand the equal pressure thing. Don't have space for 2 50 gallon tanks.

I assume your joking about pumping the mains?

Try measuring the incoming mains pressure, if close to 3 - 4 bar then ok to connect cold to shower and only pump hot. If higher then maybe a pressure reducing valve?

I still think you will need a larger cold water tank than 50 gallon even for a 3/4 bar single. As some else suggested, have you the space to fit a coffin tank or two in the eves?

Pumping mains was tongue in... Eaves tanks are an idea. Will have to rig a temp solution though as whole roof frame coming off and engineered trusses going on.