Uneven pressure in kitchen

Finnis · 7 Jan 2004

My cold water runs great - in fact, so great I get bad water hammer when I use the dishwasher. The hot on the other hand is pathetic. Pressure in the utility - the other side of the wall - is pretty even.

Have just had a new kitchen fitted but to be fair the old freestanding dishwasher I had in the old kitchen produced water hammer too so it's nothing to do with the fitters!

Hot water from tap problem didn't exist before but tap is new so it could be that.

Question is, does the pressure of cold influence the hot or are the problems independent of each other?

Ade

oilman · 7 Jan 2004

Depends where your hot water comes from. If it's from a hot water tank it may be the new tap is a high pressure tap, and the old one was a low pressure tap.

Plumber Will · 7 Jan 2004

What sort of boiler do you have...combi..back boiler with cylinder..and what make..it all helps?????

Finnis · 8 Jan 2004

Got a Stelrad boiler. Not a combi.

Didn't know you could high and low pressure taps. Any recommendations?

sterose · 8 Jan 2004

If its a Stelrad then the hot water will be gravity.

The problem with gravity, is that it has very low pressure (comapred to mains).

Just about anything under the sun could cause low flow on the hot.

But as the problem has arrived since your new kitchen, i would bet it is dodgy pipework.

Look for any signs of blockage anywhere.
In fact, it is perhaps those little silver ball valves they install, they cut the flow in half. Look for any of those valves on the hot and, for sure, remove them.

Plumber Will · 8 Jan 2004

An isolating valve not open or a flexible tap connector kinked could be the cause???

oilman · 8 Jan 2004

Didn't know you could high and low pressure taps. Any recommendations?

Search the web for high and low pressure taps.

Finnis · 9 Jan 2004

What qualifies as low pressure? I see Blanco manufacture taps which are suitable for 0.2 bar. That's as low as I've seen anywhere.

Sterose: I wouldn't know a "little silver ball valve" if I fell over it, and bearing in mind all my pipework is behind the units now I think my options are somewhat limited!

My dishwasher water hammer problem seems to have been cured by partially clsoing the isaolation valve next to it. Is this likely to have any detrimental effects in the long term?

oilman · 9 Jan 2004

Low pressure would be water from a loft tank, so say less than 0.8 bar. High pressure would be direct from the mains.

ChrisR · 9 Jan 2004

The ball valve being referred to is rather like the isolation valve on your dishwasher - though usually straight and screwdriver-operated. It won't do any harm to leave it part open.
Check your main stop cock, sometimes having it more or lesss open affects hammer without seeming to affect flow.
Otherwise a small pressure vessel (about the size of a big lemon) can be added to absorb the shock.

sterose · 12 Jan 2004

ChrisR said:
The ball valve being referred to is rather like the isolation valve on your dishwasher - though usually straight and screwdriver-operated. It won't do any harm to leave it part open.
Check your main stop cock, sometimes having it more or lesss open affects hammer without seeming to affect flow.
Otherwise a small pressure vessel (about the size of a big lemon) can be added to absorb the shock.

Wont do any harm? Silly you...

The 15mm valves have a bore of about 8mm, which is bad enough for low pressure. If the blo*dy thing is half open, you'd be lucky if you got hot water by Thursday...

My suggestion is to replace these valves with a larger bore type (i.e. Full bore valves, or a stopcock), or to dipsense with them altogether.

oilman · 12 Jan 2004

My suggestion is to replace these valves with a larger bore type (i.e. Full bore valves, or a stopcock), or to dipsense with them altogether.

But we don't know yet if there are any.

diynot

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Uneven pressure in kitchen

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