Range Powermax 155x - HW works but not CH

[lee23]

I have a Powermax 155x (open vented) which was installed in 2004 when the apartment was newly built. I’ve been getting hot water fine all year, but no heating to my radiators since trying to turn it on for the first time this winter. Here are my findings so far;

• CH pump seems to be running
• Bathroom towel radiators work fine
• No other radiators work in the flat
• Just on the radiator nearest to the boiler, after a while the (outlet?) pipe gets hot, while the other pipe connected to the TRV remains cold/lukewarm. All other pipes in all other radiators remain cold/lukewarm.
• Removing this particular radiator, water seems to run fine from both the outlet and inlet pipes.
• I have also bled all radiators – appears to be no air in the system.

Given these observations, what would you advise?

Thanks in advance

 

[Agile]

Do you have a motorised valve which isolates the rads and has failed?

Are the towel rads on the same circuit as the rads?

Its possible the CH pump is running at very reduced torque. If you think so then you could isolate and remove the head and do the finger test.

Tony

 

[lee23]

Do you have a motorised valve which isolates the rads and has failed?

Are the towel rads on the same circuit as the rads?

Its possible the CH pump is running at very reduced torque. If you think so then you could isolate and remove the head and do the finger test.

Tony

Thanks Tony,

I think the towel rads must be on a different circuit since they are the only ones that work, though I'm not sure then what is pumping hot water into them.

I don't think my boiler has a motorised valve - could not locate one. (Unless someone who knows powermaxes will tell me otherwise?)

I guess it is possible that the CH pump is running at reduced torque - cannot tell if the current speed is normal or not. I AM able to up the speed to level 3, but again not sure if it is the full speed. Will do the finger test and report back.

Meanwhile if there is anything else I can try, I'm all ears.

Thanks

 

[lee23]

... and as far as I can tell the pump is working fine.

 

[45yearsagasman]

You need to prove the pump is working and not rely on "as far as I can tell"
Remove the front screw from the pump and check that the pump is spinning. Use a small screwdriver to engage the shaft. There will be a little water coming out, so have a towel handy. Make sure all rad valves are open and if trv's are fitted make sure they are opening fully.

 

[lee23]

Yeah it's spinning and all the valves do open fully.

 

[Baxmax]

Are you sure it is the "c.h " pump you are looking at ?

 

[lee23]

I think so, it's pretty clearly marked. In any case I've checked both pumps and they are both spinning.

 

[lee23]

As an update, i have found the manifolds. All branches from the inlet manifold are hot, but all from the outlet are cold. I also notice now that the towel rads, which are the only ones that work, are also part of the same circuit. Any comment on would be welcome!

 

[gazthepottertonengineer]

Impeller has probably dropped off heating pump!

 

[Agile]

Its possible the CH pump is running at very reduced torque. If you think so then you could isolate and remove the head and do the finger test.

Tony

If he had followed my early advice then the finger test would have covered that.

However, he only seems to "think" that the pump is working!

I am beginning to think that this is a microbore system!

Tony

 

[Onetap]

As an update, i have found the manifolds. All branches from the inlet manifold are hot, but all from the outlet are cold. I also notice now that the towel rads, which are the only ones that work, are also part of the same circuit. Any comment on would be welcome!

TRVs shut? TRVs opened after winter but pins stuck down?

The CH pump on the Powermax is a 3 speed type, I think; try it on high speed. Shut all the TRVs or one valce on each radiator. Open one rad at a time and see if any flow results.

 

[lee23]

Thanks.

Have checked all trvs- dont think they are the problem.

Turned the speed up to level 3- also tried opening up the rads one by one and i do get heat from 2-3 rads closest to the boiler. (which is an improvement!) also replaced the pump but didnt help any further...

 

[lee23]

additional findings so far-

* The CH pump works and the flow manifold gets hot.

* By closing all rad valves, and turning just one TRV on, the return pipe by the base of that particular rad gets hot. (but not the pipe connected to the TRV, which is definitely the flow pipe)

* all the while the return pipe at the boiler remains cool/lukewarm..

i'm very confused

 

[Onetap]

The pump possibly isn't running. Have you checked there is a power supply to it? Does the sound change noticeably when you alter the pump speed?

There is a high-limit thermostat with a reset button within the Powermax, which shuts off the pump, but it isn't obvious what the reset button is.

Maybe there is gravity circulation going through the towel rail, possibly in reverse, and this is spinning the pump impeller, but no pumped circulation although the impeller is turning. There would be no significant flow through the radiators because the (microbore?) pipe resistance is too great.