A question for the Plumbers

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roofer

Original Poster:

5,136 posts

212 months

Wednesday 23rd July 2014
quotequote all
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

roofer

Original Poster:

5,136 posts

212 months

Wednesday 23rd July 2014
quotequote all
Sir Bagalot said:
I would be going for a Megaflowyes
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.

roofer

Original Poster:

5,136 posts

212 months

Wednesday 23rd July 2014
quotequote all
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 ?

roofer

Original Poster:

5,136 posts

212 months

Wednesday 23rd July 2014
quotequote all
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.

roofer

Original Poster:

5,136 posts

212 months

Wednesday 23rd July 2014
quotequote all
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 ...;-)

roofer

Original Poster:

5,136 posts

212 months

Wednesday 23rd July 2014
quotequote all
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.