Electric Water Heating for Studio Flat

[paulgwat]

Hi all,

First post on the plumbing forum so please be gentle!

I am an electrician but have been asked to act as main contractor on a studio flat renovation which could then lead into updating the whole block to the same spec and I need to put together various tender documents pretty quick.

The flat is a fairly basic 35sqm Studio, one bathroom with electric power shower and basin and a kitchen sink.

The block of flats only has Electricity so no option to use gas or LPG etc. Availability of Economy 7 is an open question but assume not for now.

I have no options for storing cold water so any solution needs to be mains pressure.

The initial client spec proposed the use of a multi outlet instantaneous water heater and a 9.5Kw shower - a total electrical load that the incoming supply into the flats will not support, so it is looking like a solution based around stored hot water is necessary.

I have been looking at Stiebel Eltron 50l unvented water heaters and one of these could be a potential solution, what are peoples thoughts on these? I assume they are covered by the same requirements as an unvented cylinder? My main concern here is reheat time at about 2hours on 3Kw setting although given the quantity of water stored I can't see it running out given we are talking about washing up and a bathroom sink.

Are there other manufacturers I should look at who offer better performance or better cost?

The third option I see is a simple direct unvented cylinder with a 3Kw immersion but these are much bigger and would cause some headaches re location, mainly due to weight.

I have contacted 4 plumbers today and not one of them can work on unvented cylinders/ systems, is this the norm? I don't want to be proposing something we can't find anyone to fit or maintain?

If I have overlooked any other potential options please feel free to suggest.

Regards

Paul

 

[paulgwat]

Apologies couldn't work out how to edit first post so here's a follow on question.

From the research I have done all of the unvented solutions irrespective of size require a PRV into a tundish and then in most cases it is either implied or stated that this has to run to external in metal pipework in a way to minimise issues of scalding etc.

In this situation there is no way I can run pipework external on the building (not least because I am on the third floor and have no physical access without closing a road to put up scaffolding but also because the building has been reclad and anything external like TV aerial cabling etc was removed or rerouted so will never get client sign off).

I have seen a number of posts on this forum suggesting that assuming the appropriate temp rated pipework is used then there is no issue putting the PRV discharge into the soil stack with an inline vapour trap to make sure no odour issues.

Does this approach hold water or am I going to need to get the BCO onside?

Paul

 

[Dotty]

Whereabouts are you, Paul?

Plenty of G3 guys on here.

 

[paulgwat]

The job is based in Bristol