C/H - Setting Auto Bypass Valve With Variable Speed Pump?
 

Hi,

I have just changed my pipework and have added an automatic boiler
bypass valve so the boiler (Baxi Barcelona) does not control the pump
(pump stopped and started at beginning of heating cycle). This was
required if no valve was fitted.

I have a energy saving pump (Alpha +) which varies speed with back
pressure and want to manually set the bypass valve.

The valve information asks for information on boiler minimum flow pump
head etc and to read across a graph to obtain the "setting" on my
Honeywell valve.

This all seems to be a bit complicated and I have just noticed that the
pump has 3 manual settings, the slowest is for "adjusting bypass valve"!!

How do I find the setting, do I run system until the all TRV's start
shutting (IE system reaching stable operation at nominal temperature)
then adjust the valve till it just bypasses and back it off a fraction?

The above is what I have arrived at doing some logical thinking, but I
might be wrong!

Apologies for any wrong terminology.


Regards

C/H - Setting Auto Bypass Valve With Variable Speed Pump?
 

"Peter Hemmings" wrote in message
. uk...
Hi,

I have just changed my pipework and have added an automatic boiler bypass
valve so the boiler (Baxi Barcelona) does not control the pump (pump
stopped and started at beginning of heating cycle). This was required if
no valve was fitted.

I have a energy saving pump (Alpha +) which varies speed with back
pressure and want to manually set the bypass valve.

The valve information asks for information on boiler minimum flow pump
head etc and to read across a graph to obtain the "setting" on my
Honeywell valve.

This all seems to be a bit complicated and I have just noticed that the
pump has 3 manual settings, the slowest is for "adjusting bypass valve"!!

How do I find the setting, do I run system until the all TRV's start
shutting (IE system reaching stable operation at nominal temperature) then
adjust the valve till it just bypasses and back it off a fraction?

The above is what I have arrived at doing some logical thinking, but I
might be wrong!

Apologies for any wrong terminology.

The bypass needs to open when all the valves are closed.
So close all the valves and then adjust the bypass so it closes and then
back it off so it is open.
You need to set the pump to its minimum speed when you do it so it doesn't
slow down any more and fail to open the valve in normal use.
I expect that is what the setting "adjust bypass" is for.

C/H - Setting Auto Bypass Valve With Variable Speed Pump?
 

dennis@home wrote:

snip


How do I find the setting, do I run system until the all TRV's start
shutting (IE system reaching stable operation at nominal temperature)
then adjust the valve till it just bypasses and back it off a fraction?

The above is what I have arrived at doing some logical thinking, but
I might be wrong!

Apologies for any wrong terminology.

The bypass needs to open when all the valves are closed.
So close all the valves and then adjust the bypass so it closes and then
back it off so it is open.

OK I will do that, thanks.

The reason I was not going to shut all valves was that I have 2 towel
rads which are never shut/adjusted so I thought I would never get to the
state when everything was shut!

I see that would be the worse case scenario and will ensure a flow
across the boiler. The only minimum figure I can find on the Baxi
literature is 3 litres/minute which seem quite low!

You need to set the pump to its minimum speed when you do it so it
doesn't slow down any more and fail to open the valve in normal use.
I expect that is what the setting "adjust bypass" is for.

Yep, that's what I thought



Thanks

C/H - Setting Auto Bypass Valve With Variable Speed Pump?
 

"Peter Hemmings" wrote in message
. uk...


The reason I was not going to shut all valves was that I have 2 towel rads
which are never shut/adjusted so I thought I would never get to the state
when everything was shut!

If that is the case you don't need a bypass.

Mine frequently has all the valves closed as it is controlled by 5 two port
valves that shut whenever nothing wants heat, a bypass is essential then.

C/H - Setting Auto Bypass Valve With Variable Speed Pump?
 

dennis@home wrote:


"Peter Hemmings" wrote in message
. uk...


The reason I was not going to shut all valves was that I have 2 towel
rads which are never shut/adjusted so I thought I would never get to
the state when everything was shut!

If that is the case you don't need a bypass.

Mine frequently has all the valves closed as it is controlled by 5 two
port valves that shut whenever nothing wants heat, a bypass is essential
then.

Oooops .....

Mine is the same, I have 2 2-port valves (and the two towel rads are on
one of the loops controlled by a valve), so I DO need the bypass.



Regards

C/H - Setting Auto Bypass Valve With Variable Speed Pump?
 

"Peter Hemmings"wrote

snip

The reason I was not going to shut all valves was that I have 2 towel rads
which are never shut/adjusted so I thought I would never get to the state
when everything was shut!

Don't you have a zone valve controlling all flow to the central heating, or
is this Baxi Barcelona supplying one heating circuit only and no h/w?
If it has a zone valve upstream of the towel rads then the by-pass will be
needed of course.

Phil

C/H - Setting Auto Bypass Valve With Variable Speed Pump?
 

TheScullster wrote:
"Peter Hemmings"wrote

snip

The reason I was not going to shut all valves was that I have 2 towel rads
which are never shut/adjusted so I thought I would never get to the state
when everything was shut!

Don't you have a zone valve controlling all flow to the central heating, or
is this Baxi Barcelona supplying one heating circuit only and no h/w?
If it has a zone valve upstream of the towel rads then the by-pass will be
needed of course.

Phil


Reading between the lines of the alpha + literature, if the boiler
doesnt require a minimum flowrate then is there any need for a bypass
valve ? The pump in automatic or constant pressure mode seems to cope
with zero flow .

C/H - Setting Auto Bypass Valve With Variable Speed Pump?
 

"Peter Hemmings" wrote in message
. uk...
Hi,

I have just changed my pipework and have added an automatic boiler bypass
valve so the boiler (Baxi Barcelona) does not control the pump (pump
stopped and started at beginning of heating cycle). This was required if
no valve was fitted.

I have a energy saving pump (Alpha +) which varies speed with back
pressure and want to manually set the bypass valve.

The valve information asks for information on boiler minimum flow pump
head etc and to read across a graph to obtain the "setting" on my
Honeywell valve.

This all seems to be a bit complicated and I have just noticed that the
pump has 3 manual settings, the slowest is for "adjusting bypass valve"!!

How do I find the setting, do I run system until the all TRV's start
shutting (IE system reaching stable operation at nominal temperature) then
adjust the valve till it just bypasses and back it off a fraction?

The above is what I have arrived at doing some logical thinking, but I
might be wrong!

Apologies for any wrong terminology.


Regards

The bypass valve gave the pressure it opened on a dial. So I set it at a
pressure where I knew the pump could still pump water round according to the
pump spec sheet (at the minimum speed).