Re: Anyone recommend a combi that works well on low water pressure?

[Christian McArdle]

Anyone know if it is possible to use some form of mains pressure

>hot water cylinder that would not have its output flow rate capped >by the mains inlet flow rate?

Only using advanced nuclear physics to convert energy into matter.

One other alternative is to use a tank and pumps. If you are planning a shower in the loft, this could be problematic due to the head being above the tank water level.

Then you have the choice of replacing your water main with something decent such as 25mm MDPE (assuming good street pressure), or using a pressurised storage tank, as would normally be found on a well system. This basically involves fitting a well type water system, but rather than putting it in a well, putting it in a small tank filled from your puny mains supply. The pump in the well system keeps the outlet water pressure at a nice high pressure and just tops the tank off slowly when the level drops too much.

Could be expensive, though.

Christian.

[John Rumm]

This may be well worth doing. I have a feeling the mains pressure is still fairly poor - but obviously the flow rate limitation is not as great. The current incoming pipe looks to be 1/2" copper - and I would not be supprised if its a bit constricted by now either.

Yup - sounds it!

[IMM]

Well this must be it then.

long as you have a water "pressure" of approx 0.8 bar then this works well.

Combi's: Ferrolli Modena and Dominia and the Ariston Microgenus all operate on very low pressure: 0.1 bar on the Dominia (the lowest of any combi)

Whatever you do, look into getting the mains uprated to 15mm blue plastic.

[Christian McArdle]

If I was spending the time, effort and money to upgrade my mains, I would put in something like 25mm MDPE, which will cost hardly any extra.

Christian.

[Muddy Paws]

There is a unit available that is basically a sealed cold water tank, very similar to an expansion vessel but much larger and suitable for potable water. If the standing pressure (with all outlets closed) is Ok this will provide a quantity of water at a useable pressure. I cannot recall maker etc, it was just lurking in the corner of the centre where I did my unvented training, if anyone is seriously interested I can contact them for details

[IMM]

I gave the URL