Unvented Cylinder Questions

[ln1234]

Hi Guys,

Have a few questions on unvented cylinders:

- I have a flow rate of at least 20 litres per min on Ground level (worst case scenario based on my calculations). Is that enough to provide at least 2 showers at the same time on the 2nd floor? (approx 8m higher from ground)

- Direct vs Indirect - Is it preferable to have one over the other? what is the difference in running/installation costs etc?

- Cylinder will be located on 2nd Floor level. How much likely pressure/flow rate drop would there be at source of cylinder? height approx 8 metres with 22/28mm mm pipe feed.

Cheers

 

[Agile]

People always forget to measure the pressure.

Showers need a pressure to work and measuring the open pipe flow is not enough.

Try to measure the flow with a pressure of 0.5 Bar left in the system!

It all depends on the flow rate from the two showers. If they are on gravity then tripple the flow rate they give now!

Being upstairs will probably not have a significant effect if the showers are further down but repeat flow test with a 1.0 Bar residual pressure to be sure.

Assume about £1000 - £1200 depending on size and make for an unvented cylinder. Installer need appropriate Certificate for unvented and it needs to be notified to Building control.

Tony Glazier

 

[ln1234]

Tony - thanks for replying. Understood about measuring pressure - will have to do that next.

Is there a preference for Direct vs Indirect heating methods?

Would you be interested in quoting for this work? you contact me on

Thanks

MOD

please see 14a

 

[CopperCylinderMan]

Direct - electric only - right now, its more expensive than gas. you will have to size your cylinder bigger, as its most economical to heat the tank overnight (assuming you get off peak rates) and store it till you need it during the day.

Indirect - gas or oil boiler (and some electric ones) - much faster reheat time, so the size can be smaller than the direct one.

depends on what heat source you have/are planning for your central heating really.

Flow rate - if you only have 20l/min incoming mains, then its not enough to run 2 x standard showers - Mira excell/aqualisa running at 2 bar use approx 15l/min each - thats mixed water, so for 2 simultaneous you need at least 30l/min.

If you have 28mm coming off the mains, then find an unvented cylinder with 28mm cold water controls, to give the best flow rates.

If you measure the pressure 8m below the showers, remeber you will lose 0.8 bar by the time it gets to the shower, ignoring any pipework losses.

IMHO, if your showers are 8m above where you measure the pressure you are looking for at least 30 l/min and 2-2.5 bar min to run your two showers.

HTH

CCM