I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

TIA

On 27 Oct 2005 03:31:12 -0700, "Jon" wrote:

I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

TIA

What type of shower valve do you have? A thermostatic valve would
help.

Not sure, but getting a 22mm pipe for the hot as near as possible to
the shower, with other services branching off in 15mm, might make a
difference.

My plumber disagrees, saying that it makes no odds since it is only
15mm coming from the boiler, but to me it seems common sense that it
would help smooth the flow of hot from the boiler. Sure someone will
tell us either way.


Replace 'spam' with 'org' to reply

On 27 Oct 2005 03:31:12 -0700, "Jon" wrote:

I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

TIA

What type of shower valve do you have? A thermostatic valve would
help.

Not sure, but getting a 22mm pipe for the hot as near as possible to
the shower, with other services branching off in 15mm, might make a
difference.

My plumber disagrees, saying that it makes no odds since it is only
15mm coming from the boiler, but to me it seems common sense that it
would help smooth the flow of hot from the boiler. Sure someone will
tell us either way.


Replace 'spam' with 'org' to reply

"Jon" wrote in message
oups.com...
I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

As the combi depends on a constant flow of mains water to heat up then it's
not easy to balance out changes to the water pressure due to
someone/something else using the water supply. Unless you have an elaborate
mechanism of storage tanks.

All you can do is to make sure you have a thermostatic mixer on your shower,
so if the water pressure drops, at least the temperature shouldn't fluctuate
too much. I know with my combi when someone else uses the water the pressure
drops equally across the hot and cold.

As for the heating, then I don't believe it should do that at all.

"Kalico" wrote in message
...
On 27 Oct 2005 03:31:12 -0700, "Jon" wrote:

I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

TIA

What type of shower valve do you have? A thermostatic valve would
help.

Not sure, but getting a 22mm pipe for the hot as near as possible to
the shower, with other services branching off in 15mm, might make a
difference.

My plumber disagrees, saying that it makes no odds since it is only
15mm coming from the boiler, but to me it seems common sense that it
would help smooth the flow of hot from the boiler. Sure someone will
tell us either way.

The best thing to do is run a dedicated 22mm pipe from the stopcock to the
combi, even if the mains is 15mm. Tee off the cold to shower just before
the combi on this 22mm pipe. At the stopcock tee off to all the other cold
outlets and insert a controlling gate valve here. Also insert in-line
service valves at taps and throttle them back. Then the combi and shower
will get priority.

Putting 22mm on the outlet side can work but only when feeding the shower,
and 22mm must be on the combi feed. Again this makes sure the shower gets
priority.

On 27 Oct 2005 03:31:12 -0700, "Jon" wrote:

I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

TIA
Alas one of the major drawbacks of many combis is finally revealed.
Many combis just arent up to the job of supplying two taps at once
with decent flow rate. As others have stated, check if the mixer vavle
is thermostatic,if not then fit a thermostatic mixer,thats about all
you can do apart from fitting a water storage cylinger to ensure a
decent bulk hot water supply.



Remove antispam and add 670 after bra to email

http://www.no2id.org/

"tarquinlinbin" wrote in message
...
On 27 Oct 2005 03:31:12 -0700, "Jon" wrote:

I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

TIA
Alas one of the major drawbacks of many combis is finally revealed.
Many combis just arent up to the job of supplying two taps at once
with decent flow rate. As others have stated, check if the mixer vavle
is thermostatic,if not then fit a thermostatic mixer,thats about all
you can do apart from fitting a water storage cylinger to ensure a
decent bulk hot water supply.

Bzzzt Wrong. A higher flowrate combi would solve it too.

"Doctor Drivel" wrote in message
eenews.net...

Alas one of the major drawbacks of many combis is finally revealed.
Many combis just arent up to the job of supplying two taps at once
with decent flow rate. As others have stated, check if the mixer vavle
is thermostatic,if not then fit a thermostatic mixer,thats about all
you can do apart from fitting a water storage cylinger to ensure a
decent bulk hot water supply.

Bzzzt Wrong. A higher flowrate combi would solve it too.

It's my understanding that Combi's can only ever supply hot water at the
maximum flow rate of the mains supply. Which I think mine certainly can. So
putting a higher flowrate boiler on wouldn't necessarily help

It's my understanding that Combi's can only ever supply hot water at the
maximum flow rate of the mains supply. Which I think mine certainly can.
So
putting a higher flowrate boiler on wouldn't necessarily help

If your mains is that bad, then a mains pressure hot water system is
probably a bad idea in the first place.

Christian.

In message , Mark Hewitt
writes

"Doctor Drivel" wrote in message
reenews.net...

Alas one of the major drawbacks of many combis is finally revealed.
Many combis just arent up to the job of supplying two taps at once
with decent flow rate. As others have stated, check if the mixer vavle
is thermostatic,if not then fit a thermostatic mixer,thats about all
you can do apart from fitting a water storage cylinger to ensure a
decent bulk hot water supply.

Bzzzt Wrong. A higher flowrate combi would solve it too.

It's my understanding that Combi's can only ever supply hot water at the
maximum flow rate of the mains supply.

And/or the maximum rate at which they can heat it. The mains flow in my
old house with a combi the mains flow rate was a fair bit more than the
boiler could heat. So the rate of heating was the limiting factor (as it
is in most combi installations I suspect.


Which I think mine certainly can.

If you shower really does stop (as opposed to just get bit slower) when
another tap is turned on then it suggests to me that the mains flow
isn't up to the job maybe. In the above mentioned installation, (with a
100,000 btu combi) if someone tuned on the tap in the kitchen or the
bathroom the shower flow would reduce, but it was still usable. 15mm
water supply, bath or kitchen teed off of the same pipe to the shower.


--
Chris French

"chris French" wrote in message
...
In message , Mark Hewitt
writes

"Doctor Drivel" wrote in message
reenews.net...

Alas one of the major drawbacks of many combis is finally revealed.
Many combis just arent up to the job of supplying two taps at once
with decent flow rate. As others have stated, check if the mixer vavle
is thermostatic,if not then fit a thermostatic mixer,thats about all
you can do apart from fitting a water storage cylinger to ensure a
decent bulk hot water supply.

Bzzzt Wrong. A higher flowrate combi would solve it too.

It's my understanding that Combi's can only ever supply hot water at the
maximum flow rate of the mains supply.

And/or the maximum rate at which they can heat it. The mains flow in my
old house with a combi the mains flow rate was a fair bit more than the
boiler could heat. So the rate of heating was the limiting factor (as it
is in most combi installations I suspect.

Unless you have 76kW MAN boiler

Which I think mine certainly can.

If you shower really does stop (as opposed to just get bit slower) when
another tap is turned on then it suggests to me that the mains flow
isn't up to the job maybe. In the above mentioned installation, (with a
100,000 btu combi) if someone tuned on the tap in the kitchen or the
bathroom the shower flow would reduce, but it was still usable. 15mm
water supply, bath or kitchen teed off of the same pipe to the shower.


--
Chris French

Jon wrote:

I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I wonder if the hot water flow from the boiler is all it could be. How old
is the boiler? Is your water hard and, if so, do you have an effective
(i.e. phosphor-dosing, not electronic or magnetic) scale inhibitor?

(I'm not sure if it being scaled up would cause the problem of the heating
affecting the suply of hot water, but if it is scaled up you should
definitely sort that out before trying to address other problems.)

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

You could partially turn off the service valve (if you have one - or fit one
if you don't) on the kitchen and other hot taps so that they don't reduce
the flow to the shower so much.

In message .com, Jon
writes
I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water?

Most of them do

Also, is it possible to prevent the affect
of turning on a tap in another room?

Yes, you just warn people not to do it while you're having a shower


TIA


--
geoff

Kalico wrote:

Not sure, but getting a 22mm pipe for the hot as near as possible to
the shower, with other services branching off in 15mm, might make a
difference.


That would mean twice as much water sitting in the pipe between the
boiler and the shower. If this is also used to feed a basin tap then
anyone wanting a bit of warm water to rinse their hands will have to run
off twice as much water.

IanC

tarquinlinbin wrote:

Alas one of the major drawbacks of many combis is finally revealed.
Many combis just arent up to the job of supplying two taps at once
with decent flow rate.

Even with boiler powerful enough to handler more than one tap at a time
there is still the problem that the change in flow rate will in many
cases also cause a change in output temperature of the combi.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Thu, 27 Oct 2005 12:54:27 +0100, "Doctor Drivel"
wrote:


"tarquinlinbin" wrote in message
.. .
On 27 Oct 2005 03:31:12 -0700, "Jon" wrote:

I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

TIA
Alas one of the major drawbacks of many combis is finally revealed.
Many combis just arent up to the job of supplying two taps at once
with decent flow rate. As others have stated, check if the mixer vavle
is thermostatic,if not then fit a thermostatic mixer,thats about all
you can do apart from fitting a water storage cylinger to ensure a
decent bulk hot water supply.

Bzzzt Wrong. A higher flowrate combi would solve it too.

Yes i know your a Combi evangelist doctor and i do know about higher
flow rate combis. You tend to pick things like that up after 25 years
in the industry.



Remove antispam and add 670 after bra to email

http://www.no2id.org/

"tarquinlinbin" wrote in message
...
On Thu, 27 Oct 2005 12:54:27 +0100, "Doctor Drivel"
wrote:


"tarquinlinbin" wrote in message
.. .
On 27 Oct 2005 03:31:12 -0700, "Jon" wrote:

I'm new to all this so please bare with me...

I'm having a problem with a combi-boiler and need help trying to
identify the problem -

The boiler appears to be working fine - i.e. it's able to heat the
radiators and water. However when heating water for the shower it
seems
incredibility sensitive to changes in water pressure, if someone were
to turn the tap on in the kitchen the hot water flow in the shower
completely stops. Also, if the heating is on it seems to frequently
cause the hot water in the shower to fluctuate.

I'm wondering is it possible to control the boiler so that it gives
priority to heating water? Also, is it possible to prevent the affect
of turning on a tap in another room?

TIA
Alas one of the major drawbacks of many combis is finally revealed.
Many combis just arent up to the job of supplying two taps at once
with decent flow rate. As others have stated, check if the mixer vavle
is thermostatic,if not then fit a thermostatic mixer,thats about all
you can do apart from fitting a water storage cylinger to ensure a
decent bulk hot water supply.

Bzzzt Wrong. A higher flowrate combi would solve it too.

Yes i know your a Combi evangelist doctor and i do know about higher
flow rate combis. You tend to pick things like that up after 25 years
in the industry.

It seems you never picked it up over 25 years.