Confused about combi-conventional heating setup

[deja user]

Hi all,

I've been recommended the following by a plumber, and though he seems to know what he's talking about, I'd like to know what some of you think. I've read through the deja.com archives, but haven't seen this mixed set-up, so was a bit confused...

My home:

3 bedroom 3 bathroom (1 with Bath, 1 with power shower, 1 with normal shower)

The power shower uses about 17 l/min I think, the bath uses more. All we want is to be able to have say 2 showers at once if necessary, and hot water as and when we need it.

Current setup: Cold water tank in loft Small conventional boiler - Suprima 100L Potterton Hot water cylinder (about 4ft high) Water pump - use this for the power shower.

Recommended setup:

1200btu Valliant condensing boiler Stuart Turner 4 bar pump Two hot water cylinders Expansion of the cold water tank (make it from 1 to 2) Soft water filter machine

According to the person doing it, it'll take 4-5 days. He's been rec'd by a friend and has about 30 years experience... it's just that I've been taken on so many rides it's hard to trust anyone now!!

Please let me know your comments... I'm looking forward to hassle free hot water ^_^

Raj

[Christian McArdle]

It seems odd to have 2 hot water cylinders.

Personally, if I was going for a major overhaul like this I would probably install a mains pressure system. A 200 litre or thereabouts DPS Pandora would fit the bill. This depends on your house having a meaty cold water mains supply, though. It would provide good pressure and flow without the need for a noisy pump. It would also free up the space for two cylinders and two tanks to just one cylinder and no tanks at all. Given the complexity of the proposed solution, this one would likely be cheaper, too.

OTOH, if the mains isn't up to it, the solution isn't that bad and has the advantage of redundancy, if being very wasteful of space for the tanks. The pump recommended is seriously the business and can't be faulted. The main issue would be ensuring that the cylinders are plumbed up correctly. They should each have a separate thermostat and the entire system should be S-Plan-Plus without a 3 port valve in sight. Consider subzoning the heating into bedrooms and living zones (or even finer) so that you don't heat the bedrooms during the day when not in use. Use programmable thermostats.

Another alternative is to find a large gravity cylinder. Most gravity cylinders are small affairs, but larger ones can be found, particularly easily so when not made of copper.

Finally, you don't define "soft water filter machine". Try to get exactly what is being supplied. The most commonly found types are:

1. Ion exchange water softener. Expensive to buy. Takes salt. Works very well.

1. Phosphate doser. Cheap to buy. Takes cartridges annually. Stops limescale. Doesn't soften water. It is effectively a cheap version of Calgon that releases automatically into the water.

2. Magnetic/Electronic conditioner. Variable prices. Sold by charlatans. As likely to work as casting a magic spell.

Christian.

[ski]

I would tend to go with the condensing boiler but instead of the two cylinders and cold feed tank I would install an unvented cylinder which would give you hot water at a high mains flow rate so also getting rid of the shower pumps

[Stephen Dawson]

I must be a charlatan then, because I hove sold and fitted WaterKings and Little Plumber for ages, and have never needed to go back for a scale problem. I even have a WaterKing in my house, and then kettle and taps no longer scale up.

[MBQ]

How do you know he has a high mains flow rate?

High enough for the requirement of two showers at the same time?

MBQ

[Dave Plowman (News)]

Yup. People *selling* them never have a problem.

[Stephen Dawson]

I also have one fitted in my own property, and I will not sell any I do not believe in.

[Ed Sirett]

That's the problem why I can't sell them because I don't believe in them. As soon as you ask how it works it ceases to do so. I do think there _maybe_ something in them but what exactly I can't say.

[Dave Plowman (News)]

You'll not find them for sale in the sheds round here - a hard water area. Too many irate customers and returns, according to the manager I asked.

[Stephen Dawson]

I agree with Ed, I don't know how it works, it just does.