unvented cylinder or whole house pumped

16 Nov 2013
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United Kingdom
My house has a gravity fed vented hot water which is pumped via a 2bar pump to the shower. The shower is fine but the rest of the house is rather poor. So what I was thinking was to either change the whole system to an unvented cylinder which involves rather a lot of work or install a whole house pump. At the moment all the cold water in the house is at mains pressure which is supplied at 3bar via a RPV as mains pressure is at 6bar. So if I do go for the pump option could I get away with a single outlet 3bar pump for just the hot water. Also are there any makes that are very quiet, I do have an attached garage but of course this is not protected against any frost.

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Installing an unvented cylinder is easy and quick. Less hassle then vented one.
You could simply switch the existing shower pump to supplying hot water to the house.
An intelligent plumber could convert your existing hot water cylinder into a thermal store and give you mains pressure hot water. But time and parts might mean an unvented would be easier to implement.
I faced a similar decision about a year ago, although I didn't have a pumped shower, went for the unvented cylinder and think it is great.

Fast reheat times, good pressure and high flow everywhere. No pump noise to think about. Running a bath or shower is great now.

Only word of caution is that our old low pressure shower couldn't cope as soon as it was connected to mains hot / cold the cartridge broke and needed immediate replacement.

Went for Megaflo 145i, mainly as I know others who are happy with the same.

In terms of complexity it was a case of diverting incoming cold supply from tank in loft to cylinder (rendering large tank in loft useless) and connecting cold water supply to shower and bath (used to be supplied from loft) to mains. Then connecting / wiring the cylinder. Took plumber just less than a day.

I would make the same choice again.
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One thing you will need to plan / think of with an unvented is the route of the discharge pipe especially if your tank is in the middle of your house like ours is.

The discharge pipe is a safety feature ensuring that should excessive pressure and / or temperature build up the water can escape somewhere safely.

Some information here - http://www.heatraesadia.com/docs/Megaflo_eco_-_36006062_issue_09.pdf

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