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Economy 7 HW system (Read 3729 times)

gullrock

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Economy 7 HW system
Aug 9^th, 2005, 9:55pm

I am installing an economy 7 HW system in a one bedroom flat and am trying to work out the MOST ECONOMICAL way of doing this (my time is not a factor to consider). The water is only for kitchen and washing purposes as there is a mains electic shower with no bath and no loft for a cold tank.

As the ceilings are 9ft+ high I am thinking of installing an E7 HW tank at floor level with a cold tank sited on staging as high as practical (allowing for expansion pipe and for maintenance of the ball valve etc)

The other alternative is a combination H/C tank but I cant seem to find any literature about how these work and what flow I may or may not get, or indeed even if they are what Ireally want.

« Last Edit: Aug 11^th, 2005, 12:01am by billythekid »

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chrishutt Trade Member Offline What is YaBB 1G - SP1? Posts: 28 Total Thanks: 0 For This Post: 0 Gender: Trade: Not Specified	Re: Economy 7 HW system Reply #1 - Aug 9^th, 2005, 11:07pm I would have thought that a better approach would be a 15 litre mains unvented water heater. You won't need much storage for just sink and wash basin, will you? Why bother with all that messing about with tanks, vent pipes, cylinders, etc.?
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gullrock GDPR opt-out Total Thanks: 0 For This Post: 0	Re: Economy 7 HW system Reply #2 - Aug 10^th, 2005, 8:34am Yes, that is a thought and might be much better. Those unvented water heaters are a bit expensive aren't they? Which would you go for if I did that and is installation a problem? I was also considering the possibility of a washing machine but I suppose that could be cold fill though couldn't it?
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chrishutt

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Re: Economy 7 HW system
Reply #3 - Aug 10^th, 2005, 7:48pm

Gullrock, if you read my post carefully Angry

, you will see that I referred to a 15 litre unvented tank. These are cheap to buy (£100) and simple to fit, providing you think about excess pressure discharge pipe location.

I don't see why you should need more than 15 litres storage, given that the tank will reheat in minutes. But of course it wouldn't work well with economy 7, but for low usage of hot water, is economy 7 worth bothering with? You will pay a higher rate for your daytime electric with economy 7, which includes your electric shower. Undecided

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gullrock

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Re: Economy 7 HW system
Reply #4 - Aug 10^th, 2005, 11:06pm

I actually thought that an unvented tank was a bit of a problem to fit needing all sorts of pressure relief valves and expansion vessels. Certainly 15lt should be enough. Having read the specs I presume that if I can get a pipe run of about 4.5 metres from the inlet to the heater back to the first cold tap to allow for expansion then installation is even easier. As for the overflow can you let me know if that can go upwards to discharge please?

I have actually already got E7 for heating 2 x 3.6kw Night Storage Heaters which is why I was thinking of using E7 for water heating too, however it does seem that your suggestion of an unvented HW system might be the cheapest and simplest option.

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chrishutt

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Re: Economy 7 HW system
Reply #5 - Aug 11^th, 2005, 8:50pm

your discharge can not go upwards (although I've seen a few that do, and some that are missing altogether). Why can't you go out trough an external wall? Are you in a basement?

Unvented water heaters of 15 litres or less are not subject to Building Regulations G3 and do not require same range of safety controls. they are small enough to fit under sinks, etc.

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gullrock GDPR opt-out Total Thanks: 0 For This Post: 0	Re: Economy 7 HW system Reply #6 - Aug 11^th, 2005, 8:59pm Ok that is fine as I can tee in to the sink waste if I put it under the sink. That has got to be the best way of doing it as the sink is not anywhere near an external wall. Thank you for your help. Should save me a lot by not installing an E7 tank + cold tank etc!
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chrishutt Trade Member Offline What is YaBB 1G - SP1? Posts: 28 Total Thanks: 0 For This Post: 0 Gender: Trade: Not Specified	Re: Economy 7 HW system Reply #7 - Aug 11^th, 2005, 9:09pm You cannot connect your discharge pipe into a waste pipe! It has to discharge externally where any discharge can be seen, but not where it could be dangerous (e.g. over an entrance). Please download and read installation instructions on these before deciding to proceed.
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gullrock GDPR opt-out Total Thanks: 0 For This Post: 0	Re: Economy 7 HW system Reply #8 - Aug 11^th, 2005, 9:34pm Oh. I can take it to an outside wall - just a lot more work as walls are 24 inches thick!! I was hoping to save that but it is not too much of a problem if I take it behind the kitchen units. Thanks for that advice
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