General Question regarding water supply

[jal]

Hi All,

I was wondering whether someone has any suggestions to the following:

whenever I have one of the taps on in the bathroom whether its the sink or shower, and someone is using the downstair kitchen sink tap at the same time, the water supply upstair in the bathroom tap stops until the downstair kitchen sink tap is not in use. This is really annoying especially if having shower and all the sudden the water stops due to someone having the kitchen sink tap on!

(I have a combi boiler)

Any advice/suggestions would be very much appreciated. Thanks


Regards
Jal.

 

[slapper]

You need to get Plumber in to check incoming pressure on mains cold water.

 

[Axel]

Hot or Cold or Both??

 

[jal]

Hot or Cold or Both??

Cold is fine, its just with the Hot supply.

 

[jal]

You need to get Plumber in to check incoming pressure on mains cold water.

Pressure on the incoming cold water supply is perfectly fine. Thanks

 

[Axel]

Do you have a combi boiler, a vented cylinder or an unvented cylinder?

 

[xr4x4]

you have a combi boiler, live with it.

 

[SimonH2]

whenever I have one of the taps on in the bathroom whether its the sink or shower, and someone is using the downstair kitchen sink tap at the same time, the water supply upstair in the bathroom tap stops until the downstair kitchen sink tap is not in use. This is really annoying especially if having shower and all the sudden the water stops due to someone having the kitchen sink tap on!

(I have a combi boiler)

Put simply, combi boilers are (IMO) crap. You need a HUGE capacity boiler to heat water on demand, and that means you have a boiler that's grossly oversized and almost certainly of lower efficiency than it needs to be when running a light load such as heating. For your hot water, the supply is throttled (hence why you get a crap flow rate) so that if you fully open a tap, the flow rate is not so high that the boiler can't achieve a decent flow temperature - if the vale is set too open, you end up with lukewarm water if the flow is too high.

What's happening then is that when a tap is opened wide downstairs, the water runs out of it - and because the flow rate is throttled, there is insufficient to supply that tap AND drive water upstairs. I suspect you may even find air drawn into the system through the upstairs tap, which then splurges out when the tap downstairs is closed.

I've fitted a thermal store in the flat so I could do away with the combi. The shower is so much better - just "nice and hot" rather than the hot-cool-hot-cool-... it used to be, and there's a better flow rate for filling the bath. The boiler no longer 'short cycles' all the time when the heating is on, and I can run both hot water and heating from the immersion heater if (or rather when) the boiler breaks down - hopefully I'll have less complaints from the tenants in future.

 

[Axel]

can I run both hot water and heating from the immersion heater

How many kW is the immersion?? You can heat your house with 3kW? Or do you have 3 phase going into it??

 

[jal]

I have to check the kw. the combi boiler was already fitted in the house that I purchased recently & noticed the problem with the hot water flow.

 

[SimonH2]

How many kW is the immersion?? You can heat your house with 3kW? Or do you have 3 phase going into it??

It's only a standard 3kW immersion, but it's also only a small flat ! I did try it on electric only for a while, and according to the meter it used an average of about 2kW (IIRC) to keep the place warm - and it was during some chilly weather. OK, it would be limited if the occupier wanted a full bath several times a day and/or it was siberian weather, but the beauty of the thermal store is (like a hot water cylinder) you have stored heat.

If the intention was to use electric for anything but emergencies then I'd have fitted a larger heater (or two 3kW ones), but I reckon this will do to cover for when the boiler breaks down. There is also a 2kW electric fire in the living room, so if that's used I think it should be no problem.

I posted a write up in this thread. There's a schematic of the system which should help if you've not come across a thermal store before. They are especially good if you have multiple heat sources as they form a common point that all the sources can just dump heat into - my brother has just had his house almost completely rebuilt and that has solid fuel (wood burning stove) and solar as well as a gas boiler.

 

[jal]

I've just checked the boilers manual book that was supplied by the previous owner, its a Sime Halstead Combi 30/90 boiler. CH output between 9.7kw and 23.4kw, HW outputs between 8.79kw and 26.4kw.

Hope that helps.

 

[SimonH2]

I've just checked the boilers manual book that was supplied by the previous owner, its a Sime Halstead Combi 30/90 boiler. CH output between 9.7kw and 23.4kw, HW outputs between 8.79kw and 26.4kw. Hope that helps.

They put that in to supply a house, no wonder you have a problem

It takes 4.2kW to raise 1l of water by 1˚C per second. So lets assume you need a minimum of 50˚C temperature rise (incoming water is very cold this time of year), then the max flow rate is :
26.4/4.2/50 = 0.126 l/s, or 7.5 litre/min Not much is it !

Apart from throttling the downstairs tap, there's not a lot you can do. It has occurred to me that a pressure balancing valve* in the cold water supply might help - but only by slowing your cold supply to a dribble at the shower when the hot pressure disappears.

* I'm sure someone will correct me, but I'm fairly sure you can get a valve that, instead of regulating the pressure to a fixed level, will regulate it to the pressure in another circuit. So you'd fit this valve in the cold supply after the tee off to the boiler, and get it to regulate the cold pressure to match the hot pressure downstream of the boiler and it's metering valve.

My advice, if you have the space and cash - ditch the combi and fit a hot water cylinder, or a thermal store which can buffer the heating as well. And if any plumber goes "<suck through teeth>you don't want to be doing that" - then show them the way out.

 

[slapper]

I've just checked the boilers manual book that was supplied by the previous owner, its a Sime Halstead Combi 30/90 boiler. CH output between 9.7kw and 23.4kw, HW outputs between 8.79kw and 26.4kw. Hope that helps.

They put that in to supply a house, no wonder you have a problem

It takes 4.2kW to raise 1l of water by 1&#730;C per second. So lets assume you need a minimum of 50&#730;C temperature rise (incoming water is very cold this time of year), then the max flow rate is :
26.4/4.2/50 = 0.126 l/s, or 7.5 litre/min Not much is it !

Apart from throttling the downstairs tap, there's not a lot you can do. It has occurred to me that a pressure balancing valve* in the cold water supply might help - but only by slowing your cold supply to a dribble at the shower when the hot pressure disappears.

* I'm sure someone will correct me, but I'm fairly sure you can get a valve that, instead of regulating the pressure to a fixed level, will regulate it to the pressure in another circuit. So you'd fit this valve in the cold supply after the tee off to the boiler, and get it to regulate the cold pressure to match the hot pressure downstream of the boiler and it's metering valve.

My advice, if you have the space and cash - ditch the combi and fit a hot water cylinder, or a thermal store which can buffer the heating as well. And if any plumber goes "<suck through teeth>you don't want to be doing that" - then show them the way out.

Wot a load of tosh.

 

[Axel]

Tosher

A tosher is someone who scavenges in the sewers, especially in London during the Victorian era.The word tosher was also used to describe the thieves who stripped valuable copper from the hulls of ships moored along the Thames. [1] The former activity began around the time of the construction of the London sewerage system, designed by Joseph Bazalgette.
The toshers decided to cut out the middle man and it was a common sight in 19th Century Wapping for whole families to whip off a manhole cover and go down into the sewers, where they would find rich pickings.
As most toshers would reek of the sewers, they were not popular with the neighbours. One unexpected side effect of the sewer work was that toshers - or, at least, those toshers who survived - built up a strong tolerance to typhus and the other diseases that swept the ghettos.