Hot Water on unvented cylinder

[pauliepie]

Can anybody tell me what determines the whether or not a secondar

return is required on a unvented cylinder?

The reason i ask is that a friend has a small hairdressers and has go a Ariston 210 litre cylinder and he feels the hot water flow rate i quite poor. I suggested putting a pump to the hot water but that mean a new hot water supply is required on the return. Is this correct. Any info would be grateful cheer

-- pauliepie

[Paul Barker]

Not sure I quite understand you, but I have unvented cert citb re

01939173/1

First thing to try is to run a new 25mm mdpe blue water pipe from th boundary of the property. It can actually be aranged to get the loca water supplier to provide a new connection from the main pipe in th centre of the road so you have a much better flow rate.

In the dwelling use 22mm pipe everywhere.

If you still don't get an adequate flow, then likely the water compan isn't able to supply your needs. This is not unusual in some localise areas. All that is required of them by law is that water comes out o your tap, not at any particular rate.

In such cases then the only solution is to store your own water an pump it. That is how you have to use a pump in unvented scenario.

Hope that helped.

Pau

-- Paul Barker

[Aidan]

No. If it's a new problem but an old installation, then I'd suggest you get the inlet strainer cleaned, they scale up. The system should be serviced annually. There's also strainers on some outlets and on thermostatic mixing valves which can also get clogged & restrict the flow.

The secondary return simply circulates hot water around the pipework installation, so you don't waste water and time by running off a few gallons of water before you get hot water from the tap.

[pauliepie]

Thanks for that guys, its just that i assumed if the hot water run wa more than about 12m in length then a secondary pump on the hot wate return is needed which i read off the internet somewhere. So in general, the pressure that comes into the cylinder determines th pressure on the outlet side?

cheers for your hel

-- pauliepie

[Christian McArdle]

You are getting confused. You appear to be thinking of a pumped return circuit, which is used to keep the water in the pipework hot so that the hot tap gives hot water immediately. It will have no effect whatsoever on flow rate, although might be useful if there are large runs of pipework, particularly in a commercial setting.

If the flow rate is poor, it is because something is blocking the water. Possible culprits:

1. Valves not fully open. (Open them.)
2. Pipework/valves scaled up/seized. (Descale or replace them.)
3. Pipework undersized. (Replace it)
4. Mains supply in street inadequete (Fit large accumulator or use tank and pump).

Has it ever worked well?

Christian.