Hello,

I have just installed (myself) a 3 port valve fully pumped system at
home, but when I switch on the CH the boiler only fires for around 15
mins before switching itself off

I have turned up the boiler thermostat but this makes no difference

the hot water circuit is working fine

is the most likely cause airlocks? I have bled all radiators

other possibilities:

I have wired valve/controls according to manufacturers instructions,
which has included leaving out room stat as I have TRVs on all rads and
making suitable wiring mod in wiring centre to compensate. The old
system I replaced was odd (to me) and included a powered thermostsatic
valve on the primary heating coil to the cylinder. the old controls
could turn this valve on and off and the user set the temp. it had all
sorts of balancing gate valves to provide a bypass, but when I modified
the system I replaced all pipework to the cylinder for this three port
arrangement. it has an air release valve in the relevant place, and all
feed and vent pipes are correctly placed too.


Any ideas on what my next course of action should be?


thanks

Ben

wrote in message
oups.com...
Hello,

I have just installed (myself) a 3 port valve fully pumped system at
home, but when I switch on the CH the boiler only fires for around 15
mins before switching itself off

I have turned up the boiler thermostat but this makes no difference

the hot water circuit is working fine

is the most likely cause airlocks? I have bled all radiators

other possibilities:

I have wired valve/controls according to manufacturers instructions,
which has included leaving out room stat as I have TRVs on all rads and
making suitable wiring mod in wiring centre to compensate.

Like what? You are supposed to a boiler interlock, to prevent the boiler
needlessly cycling.

The old system I replaced was odd (to me) and included a powered
thermostsatic
valve on the primary heating coil to the cylinder. the old controls
could turn this valve on and off and the user set the temp. it had all
sorts of balancing gate valves to provide a bypass, but when I modified
the system I replaced all pipework to the cylinder for this three port
arrangement. it has an air release valve in the relevant place, and all
feed and vent pipes are correctly placed too.


Any ideas on what my next course of action should be?


thanks

Ben

??? I understand the boiler shouldn't run unneccessarily, but its not
working at all. maybe i have explained myself badly...

I want to test the CH but after 15 mins the boiler turns off. it has
not even begun to heat the rads, so surely an interlock is irrelevant
at this stage? wouldn't that only be relevant if the return temp was
too high?

wrote in message
oups.com...
Hello,

I have just installed (myself) a 3 port valve fully pumped system at
home, but when I switch on the CH the boiler only fires for around 15
mins before switching itself off

I have turned up the boiler thermostat but this makes no difference

the hot water circuit is working fine

is the most likely cause airlocks? I have bled all radiators

other possibilities:

I have wired valve/controls according to manufacturers instructions,
which has included leaving out room stat as I have TRVs on all rads and
making suitable wiring mod in wiring centre to compensate. The old
system I replaced was odd (to me) and included a powered thermostsatic
valve on the primary heating coil to the cylinder. the old controls
could turn this valve on and off and the user set the temp. it had all
sorts of balancing gate valves to provide a bypass, but when I modified
the system I replaced all pipework to the cylinder for this three port
arrangement. it has an air release valve in the relevant place, and all
feed and vent pipes are correctly placed too.


Any ideas on what my next course of action should be?


thanks

Ben

Hi Ben,

Firstly, can you get any heat to the radiators when you have heating and hot
water on at the programmer both at the same time? Does the 3 port motor run
when there is a demand for heat to the rads? If not try manually opening the
3 port valve. It should show how to do this in the istructions for the
valve.

Secondly, make sure there is no air in any of the high points, if any
heating pipes are in the loft look out for either manual or automatic air
vents. open these, if there are any, to clear any trapped air.

Its always better to fit a thermostat to the system. It will stop the boiler
cycling un necessarily. Especially as they are not that expensive or
difficult to fit.

Andy

In message .com,
writes
??? I understand the boiler shouldn't run unneccessarily, but its not
working at all. maybe i have explained myself badly...

I want to test the CH but after 15 mins the boiler turns off. it has
not even begun to heat the rads, so surely an interlock is irrelevant
at this stage? wouldn't that only be relevant if the return temp was
too high?

Do you have a blockage restricting the flow somewhere, is the pump
working ?

--
geoff

wrote:

Hello,

I have just installed (myself) a 3 port valve fully pumped system at
home, but when I switch on the CH the boiler only fires for around 15
mins before switching itself off

If you have wired it as per some incorrect information published by
Honeywell then you will probably have omitted the "HW off" wire from
the programmer to the grey wire on the 3 port valve.

You also need to install a room stat and loose the trv in that room
(just remove the head)


--

When CH is turned on the pump and boiler fire up, then after 15 mins
boiler will stop but pump continues running. it is possible that one
rad down stairs might have restricted flow as my girlfriend crashed a
floor sander into it!

how can I check for restricted flow without replacing rad? I would
prefer to check other possibilities before going to this length, unless
you think this is most likely cause

thanks

ben





Do you have a blockage restricting the flow somewhere, is the pump
working ?

--
geoff

I installed AAV on pipework right next to cylinder on supply to top of
coil, and manually opened 3 port when filling to let air out. I assumed
this would bleed both DHW and CH circuits

do you think I should install a separate AAV on CH circuit ?

I will wire in stat as several people have suggested this, though the
patch I used was recommended by the Danfoss Tech Dept

thanks

Ben

My info was from Danfoss Randall tech dept, who made all of the kit I'm
using. It was a Danfoss contractors pack. I had already worked out the
fix myself and rang to check. it just involved connecting the "call"
terminal on room stat terminals to another terminal in the wiring
centre

thanks

wrote in message
oups.com...
I installed AAV on pipework right next to cylinder on supply to top of
coil, and manually opened 3 port when filling to let air out. I assumed
this would bleed both DHW and CH circuits

do you think I should install a separate AAV on CH circuit ?

I will wire in stat as several people have suggested this, though the
patch I used was recommended by the Danfoss Tech Dept

thanks

Ben


It all depends on the set up of your system. if after the 3 port valve the
pipes go up to the loft and then drop down to the radiators, then you will
need some sort of air vents on both the flow and return to clear any air
locks. This assumes that all the radiator vales including the lock shield
are open. Did you manually open the 3 port? at least that way you should
have hot water flowing towards the radiators.

Andy

thanks I will try this

thank you all for your help.

Having discussed this with various people I am convinced I have the
solution now, and I am going to draindown entire system and install
extra AAV on CH circuit and rebleed all rads. I will also install room
stat in suitable place to stop cycling in future.

I will close this topic now and hassle you all again when it doesn't
work!

cheers