Hi all

Just had old heating system (indirect tank for hot water) replaced
with closed combi.
I general i'm pretty happy with the results but was surprised to
discover that the flow of hot water is not restricted. As a result if
hot taps are turned on too far the water is cooler than required. On
reading the boiler manual (Biasi Garda he 28kw) it seems restrictors
are only fitted to the less powerful boilers in the range. it seems
that for our boiler a restrictor is not included as standard but can
be added if required.
Now i'm wondering about getting the plumber back to do this (assuming
it's not a diy job?) but not sure if it's worth bothering because:
a) maybe there are some cons against getting the flow restricted ?
presumably if flow is restricted to produce hot enough water in winter
then, in summer, when mains water is warmer the boiler could
potentially achieve a greater flow at the required temp (but we will
not be able to use this potential if restrictor fitted - if i've
understood how they work correctly?)
b) we intend to change all our taps within the next year, so maybe it
would be possible / easier to limit the flow at the tap some how?

As always any advice will be much appreciated

On Sat, 13 Dec 2008 06:51:05 -0800, Mike wrote:

> Hi all
>
> Just had old heating system (indirect tank for hot water) replaced with
> closed combi.
> I general i'm pretty happy with the results but was surprised to
> discover that the flow of hot water is not restricted. As a result if
> hot taps are turned on too far the water is cooler than required. On
> reading the boiler manual (Biasi Garda he 28kw) it seems restrictors are
> only fitted to the less powerful boilers in the range. it seems that for
> our boiler a restrictor is not included as standard but can be added if
> required.
> Now i'm wondering about getting the plumber back to do this (assuming
> it's not a diy job?) but not sure if it's worth bothering because: a)
> maybe there are some cons against getting the flow restricted ?
> presumably if flow is restricted to produce hot enough water in winter
> then, in summer, when mains water is warmer the boiler could potentially
> achieve a greater flow at the required temp (but we will not be able to
> use this potential if restrictor fitted - if i've understood how they
> work correctly?)
> b) we intend to change all our taps within the next year, so maybe it
> would be possible / easier to limit the flow at the tap some how?
>
> As always any advice will be much appreciated

It is almost always better to restrict the flow near the tap. If every tap
suffers from the same problem then restricting the inlet to the boiler
might work OK. Many boilers have valve to do just this.


--
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

> It is almost always better to restrict the flow near the tap. If every tap
> suffers from the same problem then restricting *the inlet to the boiler
> might work OK. Many boilers have valve to do just this.

Ed, Problem is with all taps and i've found the valve you mentioned so
i'll try adjusting it. Thanks for your help

I had the same problem; originally I restricted the flow after the boiler
with a gate valve (crude but convenient), but it was very noisy. I fitted a
proper pressure regulating valve on the cold water inlet to the boiler,
which is quiet and gives very fine control.

This one is from BES (there are others from BES and Screwfix)

18862
DO4 pressure reducing valve
£19.14

If your mains pressure is high you might see if such a valve can be fitted
before the cold taps as well, although that wasn't practicable in my house
because I wanted full mains pressure going to the loos and the shower header
tank for speed of filling.

"newshound" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>I had the same problem; originally I restricted the flow after the boiler
>with a gate valve (crude but convenient), but it was very noisy. I fitted a
>proper pressure regulating valve on the cold water inlet to the boiler,
>which is quiet and gives very fine control.
>
> This one is from BES (there are others from BES and Screwfix)
>
> 18862
> DO4 pressure reducing valve
> £19.14
>
> If your mains pressure is high you might see if such a valve can be fitted
> before the cold taps as well, although that wasn't practicable in my house
> because I wanted full mains pressure going to the loos and the shower
> header tank for speed of filling.

You fitted the wrong valve. That is a pressure reducing valve not a FLOW
REGULATOR.

The proper valve is:
BES Part number: 17527 flow cartridges less than £1.
http://www.bes.co.uk
This "regulates" flow, not pressure. It will lower flow and maintain the
pressure.

If a combis is rated say 12 litres/min a 12 litre cartridge can be fitted in
the cold inlet to the combi, so you always get 12 litres/min. Or, fit one
at the hot bath tap. The rest of the outlets will not exceed the 12
litres/min.

You could have a 12 litre regulator on the cold inlet and by-pass around it
with a 1/4 turn valve. Have it turned off in winter so all flow goes
through the regulator, and on in summer, by-passing the regulator. In
summer cold water mains temperature is higher and higher flowrates are
achievable.