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Vented or Unvented? Which domestic hot water system?

Postby huwtec » Fri Nov 02, 2007 8:54 pm

I was wondering if someone could please help me sort out which hot water system I need for my renovation.

We are thinking of instaling a shower unit that required a flow rate of 35 litres/min at 3 bar and we've been recommended a 26kw oil condensing boiler with a stainless steel 210 litre unvented cylinder and a secondary return pump for the domestic hot water. At the moment we have not had mains water installed and don't know the flow rate or water pressure.

Would this system be sufficient for running the shower or would it be better to go for a vented system as I hear that you can add pressure pumps to these systems? If it is better to opt for a vented system would the fact that we will be living on the first floor (i.e. kitchen and bathroom will be on the first floor) with the hot water storage cylinder and boiler being on the ground floor be a problem?

Thanks for all your help - I really need it!
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Postby bobplum » Sat Nov 03, 2007 6:51 pm

personally id go for unvented
we have this type of system installed in my house cant fault it
it would save on the space
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Postby marrtin » Sun Nov 04, 2007 1:47 pm

IF you are considering installing a system boiler and unvented mains pressure hot water storage tank - This is absolutely by far the best system. You don't need a pumped shower as the water pressure at the shower head should be at least as good.

Of course and unvented system is only as good as it's water supply. If you are fitting a new main, insist on the largest standard supply available. The largest permissible supply for domestic installations is stated in the water board's application form. Is either 25mm or 32mm. (Won't cost extra.)
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