Mains Water Pressure Problem?

[Jonleeper]

This is probably a very simple question, but I couldn't find anything on search so here goes,

We have just moved into the building site that is our new home, don't ask schools and local council, and are having a problem with the mains water pressure. The pressure is fine to run one tap but if another is turned on both drop to virtually nothing. If you wash your hands after using the toilet then the cistern does not fill up until you turn off the tap. The boiler is a one year old combi and seems to run the water and heating fine, 12.5l /min hot water flow-rate, and when you are showering it does not run cold it just dries up! Now we are intending to put another shower into a new en-suite and I was wondering if there is anything I can do to stop the loss of pressure. There is no tank in the loft at all and I was advised that using a shower pump with a combi boiler was not a good idea. Could I install a cold water tank in the loft and then run a pump from that to the water supply thus creating my own mains pressure?

Any ideas welcome as I would like to sort out the problem whilst I am building and not have to try and live with it and then decide in a few months time that I really need to deal and have to start al over again.

Many thanks,

Jon

[Jonleeper]

fatboy b said:

Why shouldn't we ask the schools or local council?

We had places in the local schools we liked for both children to start last summer, but I was warned off for a Tour and so my wife did not want to move the kids away from their established support network during such a potentially traumatic time. The schools, and the council, agreed and we set the start date for them as the bigging of the Summer Term, after the Easter break. Unfortunately the council decided to change their entrance criteria just before Xmas and took back the places without informing us, and the school rang us up to ask why we no longer wanted the places, especially as SWMBO had rung the week before to ask about uniform! I appealed to the council to give us back our places, and with a bit of top cover provided by my Chain of Command, managed to get them back but we had to start immediately or the council would take them back again. Given that we had planned the extension around my Tour and the known school dates moving the family into a building site was fairly traumatic, not only for us but also for the builders who had to reinstate some of the services, mainly in the kitchen and bathroom, that had been removed as these rooms are changing. So the wife and kids are living in part of the old house with makeshift facilities, which makes for great conversations inthe evenings, not!

[Jonleeper]

mk1fan said:

Water tank in the loft will solve your pressure problems but that is a lot of work.

Sounds like the local water board needs prodding, regularily.

Whilst I have the joists exposed in the extension and access though the window holes I can get reasonably large stuff into the attic relatively easily. I will also have to attach new pipes to all of the systems for the new kitchen and bathrooms so will have to drain down and bleed everything so I am not sure how much additional work adding a tank would be. Can I add it to the supply side and thus increase the pressure of the cold water as well? What size of pump should I be looking at, it will be a reasonably sized 1950's 4 bed when I am finished with a family bathroom and an en-suite. Is it going to be very expensive, another few hundred could be managed, a few thousands probably not. So many questions I know,

Thanks again,

Jon

[Jonleeper]

That sounds about right Ferg, the flow remains constant and is thus split across the open taps. I'll find the stopcock and see if it turned on fully, I know that the builders have turned it off at least once as they have been playing with the supply. As for the combi, we did not fit it, the previous owners did and so recently that I was not planning to change it. I will be running wet underfloor heating downstairs (approximately 90m2) and a family bathroom, with a thermostatic mixer over a bath, and an en-suite with a fully installed shower, SWIMBO has seen these large "rain style" shower heads with a diverter that she likes. The shower she has seen is rated at 7l/min and the combi is rated at 12.5l/min so it should be up to running both showers concurrently. If I need to fit a new boiler then that is a large expence that I was not planning on!

[Jonleeper]

Well the main stopcock was not fully open and so I opened it and the situation is a little better but still not really great. I will ask the water company to test the flow and pressure but I suspect that it will be ok for them but probably not for what I want to do. Do I need to replace the entire system and if so what would be best? Can I reuse the combi boiler or is it not right at all?

[Jonleeper]

So what would be your recommendation, if the water board do come back and say that the pressure and flow rate are ok. I can feed the en-suite, shower and sink, directly from the combi boiler and then feed the rest of the house from a tank? Would I need to install a cold water tank to maintain the pressure and flow on the cold side? Will I need a shower pump to feed the family bathroom?

I am getting slightly confused about the best way forward. The total hot water requirement for the house is;

Upstairs;
En-suite: Shower (thermostatic mixer with "rainwater" head and diverter), sink and toilet.
Family Bathroom: Bath with thermostatic mixer shower over and sink.
Toilet: Toilet and sink.
Downstairs;
Kitchen: Sink.
Shower-room: Electric shower (I thought that the combi would struggle with another thermostatic mixer and it will only be used very occasionally when the house is full!), sink.

The heating will be wet under-floor throughout the downstairs and radiators upstairs with heated towel rails in the bathroom and en-suite. I was going to look at the cost of radiators and see if I could replace the existing radiators with oversize items so that I can reduce the temperature of the heating side of the boiler for better efficiency.

Hopefully this makes some sense and I am not a million miles away from the right idea.

Many thanks for all your assistance,

Jon

[Jonleeper]

Well I was in the local City Plumbing store chatting about stuff with the clerk and a local plumber came in and joined in the conversation. He was of the opinion that an un-vented cylinder system was the best choice but that the pressure and flow should be ok in the area. He did state that there is a real issue with lime-scale and that he had found problems with steel pipes corroding and blocking. Now given that this house was built in the 1950's he thought that it was quite likely I have a steel pipe joining the mains to the house and that is probably hadn't been changed since it was installed. The mains have all been upgraded to plastic, he thought, but it is quite likely I have a restricted flow into the house from the corrosion in the steel pipe. The water-board have been contacted and are due to come round on Mon AM to test the pressure and flow into the house. This will give me a figure for the flow and pressure, but what should I be expecting or what is acceptable? I know that they will advise but I would like a little knowledge so that I can be, at least, a little informed when I speak to them.

Many thanks,

Jon

[Jonleeper]

That coldstream link would appear to be a good solution. The only problem is where to site the cylinder! I am turning the original kitchen into a toilet / occasional shower-room so could fit it in there, as long as they are not too large. The flow and pressure will be done by the water-board on Mon but I did a quick and dirty flow check on the kitchen tap with the kettle, marked in litres, and a stopwatch. To fill 1 litre from the tap took about 5 seconds so I think that I am getting 12 litres per minute flow. The coldstream site states that 9 litres per minute is the legal minimum but I am guessing that I will need more than that. Even so with 12 liters per minute I ought to be able to run a shower and tap at the same time. The combi is rated at 12.5 liters per minute, and I have the installation paperwork to show this was tested at install, so a thermostatic shower, max 8 litres per minute (and it is a simple old one so not that hungry), and tap, ? litres per minute but more than 4?, takes all the flow?


In addition to the information I posted before about outlets I should add that there will be a washing machine and dishwasher in the kitchen. Normal occupancy will be SWIMBO and my two school age children. I will be home as often as I can but that is likely to be weekends at most and maybe only every other one of those.

The worst case I can think of is two showers concurrently, possibly with an additional tap or appliance running. If the house is full, say at Xmas, then taking turns will have to be the rule.

[Jonleeper]

Right, nothing is ever easy (builders vs SWIMBO vs water-board contractor, and i am 100 miles away at work!) but I have some more information. The pressure and flow was tested at the internal stopcock and SWIMBO has told me that the water-board bloke said that the pressure was fine but the flow was low. Now having pressed her a little, obviously popular on Valentines when I am away, she seems to think that he said the pressure was 2 bar and that this was usual for the area but that the flow was 2 Gall per min where he would expect closer to 5 Gall per min. He apparently said that he believed that problem was our pipe to the house but that he could not check the water-board stopcock as it was the wrong type and he would raise a work order to get it changed. He also said, apparently, that if we ran a new pipe they would connect it free of charge to the mains. SWIMBO asked where the water-board stopcock was and was shown it directly in front of our house about 5m away from our external wall.

My understanding is, therefore, that I can expect 22.5 litres per min at 2 bar at best and only if I renew the pipe. This should be enough but if it drops then I might start to suffer. Now I can replace the main, that seems a given, but would it also be beneficial to install an accumulator as well and how expensive are they? I not from the coldstream page that they don’t give prices or dimensions! Can I place this sort of accumulator externally, there is space to build a small “outhouse” under the kitchen window to house it and that would provide a neat solution directly on the incoming water main so require less internal modification to the plumbing.

Sorry to add questions but the responses so far have been very helpful,

Jon

[Jonleeper]

Well I have discussed the problem with the water board and they have agreed to fit a 22mm plastic pipe to their main free of charge when they change the stopcock. I am waiting to here when that is likely to be but I can plan and install the internal fittings based on this occurring at some point. They cannot guarantee 5 gall per min but believe that this is likely. I, therefore, think that fitting an accumulator into the system would be a good idea and can only assist if the flow is not up to scratch or my demands increase for a short period. Also I have not yet created the walls for the downstairs “wet room” so can amend the plan to fit in what I need to.

Ferg / anyone else,

I am having trouble tracking down an idea of the size and cost of these systems! City plumbing is my local stockist, supposedly, and I have an account with TP so am happy to use but cannot find it on their website. I guess I would need a minimum of about 80 litres, a 10 min showers worth, but cannot find the details of anything! What sizes do they come in and what do they cost? Sorry to be a pain and thanks for all your assistance thus far,

Jon