On Tue, 12 Aug 2003 17:27:45 +0100, "IMM" wrote:


"Kevin Campbell" wrote in message
...
Hi,

I am replacing my current 20 yr old HW cylinder and am considering
installing a mains pressure unvented system to remove the need for a
shower pump.

Kevin

Consider getting a combi to supply the showers only. Then no expensive,
noisy, vibrating, troublesome power shower pumps. Have the CH section as a
conventional system with a 3-way "diverter" valve, not mid-position. As the
combi's water section will only be used for showers, once or twice a day,
they last quite a time as they are not excessivly switching in an out. All
the water system, except the showers will be at low pressure and high flow.

If you are replacing the cold water tank think about a "combi cylinder".
Have a 50-50 split of hot water and cold water storage. Have the cold water
section 115 litres and take all the cold supplies off the cold water
section. This way using a combi boiler for the shower side you eliminate
the cold water tank in the loft, or put the combi cylinder in the loft (well
insulated of course) and have a larger airing cupboard. Telford do the
Trident, which has a 115litre/115litre split. have a look at their web
site. Combi cylinders are simpler and quicker to install.
http://www.telford-group.com/trident.htm

Some cylinder makers will provide combi cylinders to order, in that if you
wanted a 115 litre hot section and 115 litre cold section and appropriate
tappings, etc, they will provide it.

So you would have:

1. A combi boiler supplying any high pressure showers.
2. A combi cylinder with a large cold water section. providing low pressure
hot and cold water.
3. A DHW priority system.
4. No tank in the loft, or
5. A combi cylinder in the loft and a larger airing cupboard.

This is a cost effective way to get high pressure showers and rid of a
separate cold water tank, the only points you need high pressure.


There are a number of pitfalls for the unwary in this.

A Google search for previous threads on the limitations of this
approach would be advisable



---

..andy

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