Hi,
Have moved into a house, and should have really turned on the hot tap
before we purchased, but we didnt and are now left with a dribble of a
shower. The property is a 1920s semi with a baxi WM 532 RS boiler, 8
radiators one bathroom usual appliances and an airing cupboard with a
hot water cylinder that has very poor insulation. In the loft we have
the usual header tanks (Not very high). Although the boiler works
perfectly never even hear it, we were going to look at replacing with
a more efficient one and was thinking of a combi, luckily we didnt
make that decision.

We are now looking at replacing the ho****er cylinder with either a
pressurised unvented cylinder, however my only concern is where the
pressure relief would be run, also the mains supply is only 15mm pipe
with no possibility of upgrading (as its a shared supply with next
door), also I have found out that my boiler would not be suitable for
this type of system so would require upgrading.

The other possibility is the mains pressure vented cylinder but know
little about these, would they offer the same pressure as the unvented
type? also have been looking at boilers and most say 22mm gas inlet
the supply to the boiler is only 15 mm would this be a problem?

So in summary my questions a
1) What would be best a vented or unvented mains pressure HWC?
2) Would increasing the header tank by a meter benefit the shower
much? (at present theres only bout 1/2m drop from the tank to the
shower.
3) Will the 15mm gas supply be a problem?
4) Will the 15mm mains water in let be a problem?
5) what rough cost im in Essex.

Thanks for any help
Olly

In an earlier contribution to this discussion,
wrote:

So in summary my questions a
1) What would be best a vented or unvented mains pressure HWC?

Do you really want either - see below?!

2) Would increasing the header tank by a meter benefit the shower
much? (at present theres only bout 1/2m drop from the tank to the
shower.

No.

3) Will the 15mm gas supply be a problem?

It probably would if you wanted a combi-boiler capable of producing
'real-time' hot water at a decent rate.

4) Will the 15mm mains water in let be a problem?

Very probably. Measure the flow rate at your main inlet point - probably the
kitchen tap. If it's less than 20 litres/minute forget a mains-pressure hot
water solution, be-it combi, non-vented hot cylinder, or thermal store.

5) what rough cost im in Essex.

No idea.

It seems to me that you are overlooking the most obvious - and almost
certainly, cheapest - solution, which is to install a shower pump. It needs
to take its hot feed from the HW cylinder (preferably via an Essex or Surrey
flange, but that may not be necessary) and its cold feed from the cold
header tank. That will give you a decent shower for very little effort.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On Sun, 30 Sep 2007 13:13:57 -0700, ociaravella wrote:

1) What would be best a vented or unvented mains pressure HWC?
2) Would increasing the header tank by a meter benefit the shower
much? (at present theres only bout 1/2m drop from the tank to the
shower.

Have a look at:
http://wiki.diyfaq.org.uk/index.php?..._Water_Systems
http://wiki.diyfaq.org.uk/index.php?title=Showers

--
John Stumbles

Xenophobia? Sounds a bit foreign to me.

On Sep 30, 9:13 pm, wrote:
Hi,
Have moved into a house, and should have really turned on the hot tap
before we purchased, but we didnt and are now left with a dribble of a
shower. The property is a 1920s semi with a baxi WM 532 RS boiler, 8
radiators one bathroom usual appliances and an airing cupboard with a
hot water cylinder that has very poor insulation. In the loft we have
the usual header tanks (Not very high). Although the boiler works
perfectly never even hear it, we were going to look at replacing with
a more efficient one and was thinking of a combi, luckily we didnt
make that decision.

We are now looking at replacing the ho****er cylinder with either a
pressurised unvented cylinder, however my only concern is where the
pressure relief would be run, also the mains supply is only 15mm pipe
with no possibility of upgrading (as its a shared supply with next
door), also I have found out that my boiler would not be suitable for
this type of system so would require upgrading.

The other possibility is the mains pressure vented cylinder but know
little about these, would they offer the same pressure as the unvented
type? also have been looking at boilers and most say 22mm gas inlet
the supply to the boiler is only 15 mm would this be a problem?

So in summary my questions a
1) What would be best a vented or unvented mains pressure HWC?
2) Would increasing the header tank by a meter benefit the shower
much? (at present theres only bout 1/2m drop from the tank to the
shower.
3) Will the 15mm gas supply be a problem?
4) Will the 15mm mains water in let be a problem?
5) what rough cost im in Essex.

Thanks for any help
Olly

Also look at heat banks.

A

Yeah probably should have said we did look into the pump situation,
fitting a single pump for the HW would be no problem, however because
of the setup fitting a twin pump for cold water as well wouldnt be
easy and wasnt too keen on the noise

Well just tested flow rate and its 20 litres a min. Would this be
sufficient for a mains presured hot water cylinder such as megaflo or
would I require the pressure of the water as well. Does this mean that
in theory a shower would produce about 40 l/min if both hot and cold
are fully open?

In an earlier contribution to this discussion,
Olly wrote:

Well just tested flow rate and its 20 litres a min. Would this be
sufficient for a mains presured hot water cylinder such as megaflo or
would I require the pressure of the water as well.

Flow is more important than pressure - unless you live at the top of a
sky-scraper.

Does this mean that
in theory a shower would produce about 40 l/min if both hot and cold
are fully open?

Only if you can find a way of defying the laws of Physics! g

Of the cold water coming into the house, some will go to the cold tap and
some will go into the hot cylinder, expelling hot water to the hot tap. But
you've only got 20 litres/min in *total*. Where do you think the other 20 is
going to come from?
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On 2007-10-01 19:18:37 +0100, Olly said:

Well just tested flow rate and its 20 litres a min. Would this be
sufficient for a mains presured hot water cylinder such as megaflo or
would I require the pressure of the water as well.

That isn't how it works. Pressure is not the same as flow.

20lpm would be just about enough for one shower with single, simple
shower head - i.e. not a drencher or ody jets etc.



Does this mean that
in theory a shower would produce about 40 l/min if both hot and cold
are fully open?

No it doesn't. 20lpm is the *total* coming into the house. Some
will go to the shower as cold water, while some will go via the
cylinder, but it can never exceed 20lpm.

The only way that you can make a difference to that is via some means
of storage. This is why roof tanks can deliver large volumes of water.

On Mon, 01 Oct 2007 23:19:49 +0100, Andy Hall wrote:

On 2007-10-01 19:18:37 +0100, Olly said:

Well just tested flow rate and its 20 litres a min. Would this be
sufficient for a mains presured hot water cylinder such as megaflo or
would I require the pressure of the water as well.

That isn't how it works. Pressure is not the same as flow.

20lpm would be just about enough for one shower with single, simple
shower head - i.e. not a drencher or ody jets etc.



Does this mean that
in theory a shower would produce about 40 l/min if both hot and cold
are fully open?

No it doesn't. 20lpm is the *total* coming into the house. Some
will go to the shower as cold water, while some will go via the
cylinder, but it can never exceed 20lpm.

The only way that you can make a difference to that is via some means
of storage. This is why roof tanks can deliver large volumes of water.

I declare a plague on both your houses.

It depends on the distribution of the flow resistance a significant
amount is almost certainly the last 0.5m to and through the kitchen
sink tap, especially if flexibles have been used. You might not get
a lot more out of the sink even if the supply to it was in 32, 28, 25 or
22.

So you will get more total flow, certainly not double, and more
than none extra. Anyway 20l/min is quite good for a shower for most people.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

Thanks ed, I was a bit confused that if one tap was turned on the flow
would drop significantly obviously it does but I would imagine a
combined flow of 25-30 L/min not unreasonable. The cold inlet is only
2-3m from the bathroom at max, and the same from the airing cupboard,
all fed by 15mm pipe.