Best option for pressurising hot water system?


I live in a modestly sized 70's detached house with a gravity fed hot water system. When we had our kitchen face-lifted a couple of years ago I installed a contemporary mixer tap which I did not realise at the time was only suitable for HP hot water systems - as a result the hot water flow is very poor from that tap.
I am about to strip out my bathroom and want to install a very contemporary bathroom and, of course, want to finish the job off with very contemporary taps. The problem is, of course, that with the cold water storage tank being just about 1 metre above the basin taps, the water pressure at those taps will be around 0.1 bar and very few contemporary taps are suitable for pressure that low. I would also like to get rid of my existing electric 'power shower' and replace that with a simple contemporary mixer unit. Clearly I cannot do that with hot water pressure at 0.1 bar.
So - what's the solution? I understand that I have three options: 1. Switch to a combi boiler. 2. Install a shower pump (which I would like to pressurise the entire house hot water system). 3. Install a mains-fed pressurised hot water cylinder.
I'm not too keen on a combi because it seems that almost every one I know who has a combi has problems with it - not just with regular reliability problems, but also with hot water flow problems. My existing conventional boiler is now over 30 years old and has only ever required a thermocouple replacement! The other problem with a combi is that my boiler is situated inside our attached garage and I'm concerned that it may take a long while for hot water to reach the taps from that isolated location.
A shower pump pressurising the entire house would probably be the cheapest option - but I understand that they can be very noisy - and because they operate on a pressure-switch principle, will regularly 'cycle' in order to re-build pressure in the system and this can be annoying - particularly during the night.
The final option is to replace the standard hot water cylinder with a mains-fed cylinder which would (it appears) resolve my hot water pressure problems with very few drawbacks.
I would be interested in knowledgeable opinions on these three options and also advice on whether a mains fed cylinder could be installed in the loft thus allowing me to enlarge bathroom space by removing the airing cupboard and giving me space to install a walk-in shower.
Cheers!
Kev
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Uno-Hoo! wrote:

Have you looked in the loft to see if it would be possible to put in a (possibly much smaller) header tank, much higher in the loft? Worth considering, possibly. Not an option for me, unfortunately.
I am off mains water so don't have any of the mains-pressure options. A pump and pressure vessel (not a shower pump) in the loft *doesn't* cycle regularly - unless you have one heck of a dripping tap - as the pressure vessel meets the first 10 litres demand, without the pump operating.
Noise is not a problem as it is mounted on an insulated raft with a box lined with acoustic tiles sat on top of it. It only runs when water is being drawn and the noise of the latter totally masks it, apart from the 20 secs or so it runs on after the water flow stops - which you can only hear if you listen for it.
However, it costs me about 220GBP a year to run at present electricity costs.
I'd go for a mains-pressurized system like a shot, if one was available for me. Just on running cost. However, my bathroom shower has the equivalent of 45 ft of pressure head instead of the about 45cm that it would be otherwise. You wouldn't want more..
--
Sue









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Not sure if I'm knowledgeable, but I have an opinion....
We debated very similar issues (for a mid-60s detached) and took the plunge last year to go for option 3. Not cheap (this was not DIY...!) but we're delighted with the result and would def do the same again.
We, too, had heard unfavourable comments re option 1 - esp whether a combi can cope with demands of a larger house.
We had option 2 in our last house - used for showers only. It wasn't too noisy and (unlike Sue P's) prob wasn't sound-insulated that well. But it only clicked in while shower was running, and no-one complained.
Re. location for option 3, the cylinder is a large thing - and when all the piping and sundry gadgetry is completed, closely resembles Sellafield. We know a few people who've installed them in their garage but we opted to "sacrifice" a modest walk-in larder in the kitchen, and it all fitted neatly. In return, the alcove where the old floor-mounted boiler stood is the new larder (we fitted a wall-mounted balanced flue thingy in the cloakroom), and of course the old airing cupboard is now a really useable storage space. (We added a tiny rad in there, to keep SWMBO happy.) And a further bonus is that the storage tanks have vanished from the loft, which not only freed up more space, but does away with any concerns about pipes freezing up there.
As far as "cylinder to tap" times - no problems. Certainly quicker than previous set-up. I think the key is not to have too large a pipe diameter - hence less water to shift. But I'm not sure about the technical issues when it comes to spec-ing pipe sizes.
One further tip - we installed assorted mixer taps (designed to cope with the higher pressures). By adding little in-line 1/4 turn valves on the feeds to each tap, adjusting pressure / volume on each was a breeze, whereas the adjustment options within the taps themselves would have been tiresome.
HTH - please let us know what you decide.
--
Martin






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Martin - very many thanks for your prompt and detailed response - it was very helpful. I've arranged for a couple of heating engineers to call around over the next couple of weeks (they all seem to very busy!) and will discuss the various options and costs with them. Would you mind me asking the approximate cost of your conversion to a mains-fed cylinder?
Kev
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< snip >

Not at all - but it may not help you on this. We had an all-up fixed-price quote, which included stripping out and refitting 2 bathrooms and a cloakroom. Replacing nearly every rad in the house - inc 2 large "ladder" style bathroom rads - and new lock-shields & TRVs on existing rads. Flushing all pipework which remained. Splitting up and down heating into 2 separate zones, all new controls (inc radio wall stats), new boiler in a different part of the house from the old one, water softener, outside tap, removing all old tanks etc. We provided the bathroom suites, plus builder, spark and endless cups of tea :-) The plumber supplied everything else.
So all up, his charge was about 8.5k + vat. This is top-end of the price range, but we knew the reputation of the plumber and (despite virtually an hour's drive each way) he always arrived when promised, tidied up each day, and we had water back on every night. The hassle we avoided (e.g. builders and sparks not hanging around waiting) was worth foregoing the possible saving had we shopped around more. Oh - and he didn't stuff us for extras afterwards!
--
Martin





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OK - thanks for that. Fortunately I wouldn't require anything beyond the replacement of the cylinder and the associated plumbing in. I'll have to wait for the quotes to discover the damage!
Thanks again.
Kev
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To change from a Gravity fed system to a mains (unvented) system can vary massivly as your mains coing into the property may need upgrading also as most manufacturers insist on a 25mm supply to the cylinder. This would have to be done from the street and right upto the cylinder. now depending on how far it is to renew the mains i would give a ball park figure of 5k + vat to supply and fit the unvented cylinder.
Hope this helps
Plumbline direct
Gulp!! OK! The house was built mid-1970's and I think that the cold supply to the storage tank in the loft is already 25mm. I haven't been up into the loft to check but the supply pipes run up through the bathroom airing cupboard which is situated directly below the storage tank. I've just had a shower and so the cold storage tank has been re-filling. The coldest vertical pipe running up into the loft is certainly 25 mm so I suspect that the 25mm feed is already there for diverting to an unvented cylinder. With that in mind, are you able to give a revised installation figure? A quick Google shows me that the average price for an indirect unvented cylinder of the capacity I would require would be around 500 - 600. With that in mind, and assuming the necessary pipework and 25mm cold water feed is already within inches of the new cylinder, surely the necessary plumbing would not be too expensive? Just as a matter of interest, I installed our existing bathroom myself some 10 years ago and I did all the plumbing for that myself. I changed the old bath (which had taps and plughole at one end) to a double ended bath with taps and plughole in the middle and consequently had to extend the cold and hot water pipes and relocate the drain. I have self-fitted TRVs to all (but one) of my radiators, and had to extend the pipework in order to do that. I am, therefore, quite competent in straightforward plumbing. But what about replacing a conventional vented cylinder with an unvented cylinder? Beyond simple plumbing would you say? Is there any particular task involved in such a job which is beyond just pipework re-working?
Kev
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I suggest you find a mate who's already got one, and go and look. I think it's very complex, especially if working in a confined space (hence my earlier sellafield quip), but I'm no plumber :-((
Do make sure you get adequate capacity - both for the cylinder and the boiler.
--
Martin



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Thanks Martin. You're probably right - and I wouldn't want to get stuck in the middle of the job with no hot water and no central heating (because the indirect heating loop would be disconnected)! I've got my first plumber/heating engineer coming early Friday morning so he should be able to answer all my queries. (Although I am unlikely to get an unbiased response to a query about DIY installation!)
Kev
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You are obviously getting too big a pension.
-- x If you have been, do you help the aged? /|\\
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