Hot water pressure

Help please....
I've got about 2 bar coming into my Victorian house in London. My new multi-head shower needs at least 3 bar (not sure of the flow rate).
A Conventional system will take up too much room and require reinforcement in the loft area
What options do I have? I have ordered a 4 bar pump but have been led to believe that this is only suitable for a convential system as opposed to a combi or Megaflow system.
The house has 3 bathrooms, only one requires high pressure and high flow rate, but I do need the ability to have at least 2 hot showers at the same time.
Not really a tall order I would think? What are my options?
Many thanks in advance...
P.S A water softner needs to be placed somewhere...
3D
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wrote:

The more important point is what is the flow rate? You can have perfectly good pressure (although this isn't brilliant), but a lousy flow rate.
COuld you maybe measure the flow at a tap (normally the kitchen cold tap). THis can easily be done by taking a vessel of known size (e.g. a 10 litre bucket) and timing how long it takes to fill. You can then do the sums to work out that flow rate in litres per minute.
It's pointless getting into discussions about different types of system unless the flow is good enough to provide what you need.
To run two normal showers you need to have at least 10 l/min each, preferably 15. Your multihead one probably needs 15 - 20 for results that make it worthwhile - so realistically 30 l/min for the property is the minimum.

If it turns out that you have an inadequate water flow, you will have the choice of upgrading the supply from the road or of using a conventional system with a roof tank and a pump.
If the flow is adequate, then this implies some sort of instant heat solution.
For this, you could use a combi boiler, except that at the flow rate you need, even a large one is going to fall short in cold weather and you would be running the showers at lower than normal flow. Two boilers could be used, but you need to watch out for the total heat input requirement. A domestic gas meter (IIRC) is able to deliver a supply for up to 62kW of heat equivalent and large combi boilers are in the 28-30kW range, meaning nothing left for other requirements. In this scenario, if you could split the requirement appropriately, you might be able to go for one large and one small or something.
A heat bank or thermal store are other approaches. These use a cylinder of water heated by the boiler to 76-80 degrees. This is then used to heat the water indirectly. You do have to find some space for the cylinder, but a large roof tank is not needed - just a small CH one. Some of these appliances have the header tank integral with the cylinder. These are able to deliver a lot more heat than a combi does (could be as much as 200kW) so are less likely to run into difficulties when the water is really cold. You can also arrange that the boiler comes on and starts replenishing the stored heat as soon as it starts to be used. However, the store cylinder does need to be adequately sized to deliver the output heat for as long as is required. If you are drawing stored energy at a 100 kW rate to heat the water and replenishing from the boiler at only 30kW, the stored heat runs out eventually and the system becomes, in effect, like a combi.

I would hold off on the pump until you have the rest figured out.

You wouldn't think so, but this is asking a lot unless you have a good flow of water, so that's the place to start.

That also needs to be a high flow model. Most are these days, but it will have something of a reducing effect on flow. Generally they are quite small so finding a home should not be too big an issue.
It may be prudent to check the cold mains and then get a softener supplier in to do a demo. Measure the rate that you get then and see if it is enough.

.andy
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8/10 Andy. I have taught you nearly well. You know it is always that last bit that is elusive.
You flailed on the softener. He can use a phosphor descaling canister which is only 45 from B&Q. And you failed on the combi. Many high flowrate combi's can deliver the flowrate, and you don't know the flowrate yet. Keep trying though. I will step in when you don't get it right.
Keep up the good work.
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I didn't flail anything. Are you into flagellation?

He could do, but it isn't a water softener, and that was what was mentioned. As you well know a phosphor descaler only does that specific job, it does not soften the water.

I didn't fail on anything because I wasn't taking any test.

Precisely, which is why I left the issue open, simply pointing out that the high flow rate that is likely to be required, may well be beyond the abiliy of one combi, always assuming that the mains supply can deliver the flow.
.andy
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Yes it is. It may be possible to use more than one. .andy
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On Tue, 26 Aug 2003 08:04:47 +0100, "stuart noble"

That's worth knowing.
I wonder if we could commission him to make some stocks for the village idiot?
.andy
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What part do you play? The wench at the ale house?
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Large? They can be much larger than that.
If using two combi boilers one can supply heating for downstairs and one for upstairs giving natural zoning and both zones on separate timeclocks.
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Typo, I meant 50kW.
Even at that heat input, e.g. a Micromat EC38 which has 46kW input for DHW the flow rate for 35 degree temperature rise is only about 19 litres/minute, which is probably not enough for this application.

True, but two large boilers are going to require an upgraded gas supply, I suspect. The issue is producing a large enough flow of hot water to run a multihead and a normal shower simultaneously....
19-20 litres/min is probably not going to be enough.

.andy
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Gas pipework still needs to be adequate, as does the rest of the delivery system including main from the road, regulator etc.
I had understood that Transco installs larger versions of all of these if the supply requirement exceeds 62kW. That being the case, do you think that they would support the idea of exceeding this figure on a domestic supply?

That's ultimately going to be the case with any mains fed water heating system.

I think that that is questionnable. If a boiler running at 46kW input can generate 18 litres/min, then selecting 62kW worth of combi in two boilers would suggest a production rate of 24 litres/minute. Even assuming that the water supply is up to it, this rate is only barely adequate to run a multihead and a standard shower simultaneously.

Using the very cheapest products on the market, and not including installation costs.

That would involve extra pipework and valves.

Maybe, but it would be a pointless saving if it was not fit for purpose.

.andy
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wrote:

I'm not sure as these bastards are out to make money not provided a service. The old British Gas Corpn, certainly would. I can recall a house with three 100,000 Btu multi-points and the supply uprated at no extra cost to the customer. It only required a larger meter.

But it never runs out of water!!!!
And always backup if one drops out. No very large space consuming and expensive stored water cylinders for either: heat bank, unvented or vented cylinders. Multi-head showers use a hell of a lot of water and people tend to stay in them longer, especially people using them for therapeutic reasons. A simple, cheap and effective solution.

That is decent mid priced kit. Buying two combi's will give a discount from a dealer.

Not it would not. The heads on the multi-head shower can be split between combi's. If one combi drops out just don't use the cold head and the other combi and head supplies.

It should be.
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Daniel Loshak wrote:

And won't provide 3 bar.

So what system do you have? How is your hot water heated?
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