New houses - no combi boiler!?

On Wed, 16 Jan 2008 09:46:34 +0000 someone who may be Mark wrote this:-

Certainly a problem with the installation in the storage system. A separate pipe should have been taken from the cold water storage tank, directly to the shower and feeding no other fittings. Then flushing a toilet would have no effect on the shower.

If you have mains water pressure at the bottom end of the scale - and very many do - then other use of that main while showering might well effect things with a basic shower unit.

Good design of a storage system can prevent it showing this effect. It's not really possible to modify a poor mains water supply.

The same with a combi: a separate dedicated cold feed pipe back to mains stoptap. And all water appliances balanced so as to not rob the combi or shower.

Not in this case - it was a venturi shower.

M.

Even here with good pressure, a refilling cistern has a *noticeable* effect on hot water pressure/flow.

I suspect the culprit is the softener. Its not enoughto worry about and hot and cold rates are affected equally so its not irriting in terms of temp changes.

On Wed, 16 Jan 2008 11:25:39 +0000 someone who may be The Natural Philosopher wrote this:-

In a storage system? If so, vented or "unvented"?

On Wed, 16 Jan 2008 11:25:28 +0000 someone who may be Mark wrote this:-

Then it was suffering from the fashion of connecting all cold appliances to the mains. Most are best fed from a storage tank in my view.

The message from The Natural Philosopher contains these words:

Definitely but someone has to challenge the rubbish Dribble spouts otherwise gullible newbies might be taken in by his bogus claim to expertise.

Actually it wasn't. Flushing the toilet caused the shower to go scalding and then freezing but the toilet was fed from the cold water tank.

I never figured out why it affected the shower so much.

M.

Unvented.

Its all a question of where the bottleneck is. In my case, its the softener.

Disregarding the kitchen cold tap, all other flow goes via that.

The shower must have its own dedicated cold feed from the cold water tank, then no influence from the cold services. Also the cold feed from tank to cylinder must be large enough to cope with shower and another draw off - this must be dedicated to cylinder supply only. That is why it is usually

Cold water tank/cylinder setup is a little complex and pipe intensive and expensive to install.

Take a diagram of a cold water tank/cylinder system and turn it on its side. Replace the tank with the cold water mains, the DHW cylinder with a combi or unvented cylinder or heat bank and that is how a mains pressure system should be fitted, using smaller bore pipe where necessary.

Please put me on your killfile. It is good for you.

On Thu, 17 Jan 2008 11:06:33 +0000 someone who may be Mark wrote this:-

Then I can only suggest a mains supply to the shower that was below specification.

The message from Mark contains these words:

If shower fed from mains, then flushing toilet fed from header tank would cause level in the tank to drop, ballvalve to open, leading to a drop in the mains pressure as the mains has now to feed the header tank as well to replenish the water used.

Is that like the wind supply to all the windmills ever installed windmill that was below specification :-)

On Thu, 17 Jan 2008 15:33:39 GMT someone who may be Appin wrote this:-

Indeed. It indicates that the mains supply was probably below specification.

Ah! Yes, there was a restriction in the mains (seized stopcock & short length of 15mm pipe). I'm suprised it had so much effect.

M.

On Mon, 21 Jan 2008 10:02:41 +0000 someone who may be Mark wrote this:-

Glad the problem is solved, even if it is rather late in the day.