scalding hot new Danfoss c-2 TRV cold lockshield and new radiator only hot at top .

[big john hog]

I have recently replaced all fourteen Stelrad radiators eight singles four doubles and two chrome towel radiators on small bore 10 mm piping in my four bedroom detached house.The Grundfoss pump is ten years old and sounds good .no bearing rumble.The Ideal classic ff 350 boiler is twenty years old but has been serviced regularly.Even when the balance has been turned down to a quarter of a turn on all the lock shield valves and the problem radiator furthest away has the lockshield fully open and with the pump on speed setting three .the radiator furthest away has a scalding hot Danfoss TRV and the lock shield remains cold.The system has been cleaned with F3 and flushed .The radiator has been removed from the wall and flushed manually and there was no sludge deposits in the radiator .Eventually after about an hour the radiator heats up and the valve lock shield valve is slightly warm.The boiler is set to three.My plumber has agreed to replace the pump with the new grundfoss ups3. In your professional opinion do you think that this will solve wot appears to be a pump problem .I have carried out the usual test of shutting down all the radiators and running the system .The radiator gets scalding hot together with both valves .Many thanks

 

[ShaunCorbs]

Is this the only problem radiator?

 

[cjg]

try re balancing your c/h

 

[big john hog]

Is this the only problem radiator?

Yes all the others are scalding hot

 

[ShaunCorbs]

What happens if you shut half of your working rads via the trvs ?

 

[big john hog]

try re balancing your c/h

Many thanks .How do you mean by re balance

 

[big john hog]

What happens if you shut half of your working rads via the trvs ?

I have seven rads upstairs only four have trv valves seven down stairs four with trv valves

 

[ShaunCorbs]

Turn the 4 off down stairs does the problem rad heat up

 

[big john hog]

Turn the 4 off down stairs does the problem rad heat up

Just turned four trvs off downstairs including the problem rad one which has a trv on it and its scalding hot

 

[ShaunCorbs]

Leave the problem rad open / calling

 

[big john hog]

Just turned four trvs off downstairs including the problem rad one which has a trv on it and its scalding hot

Correction just checked again and problem rad starting to go cold

 

[big john hog]

Leave the problem rad open / calling

ok I will run down stairs and open trv

 

[big john hog]

ok I will run down stairs and open trv

Problem radiator now getting hot

 

[ShaunCorbs]

Fully hot / acceptable?

You either have a balancing problem or pump is weak

 

[ShaunCorbs]

RAS-B2

Danfoss radiator thermostats maintain constant desired room temperatures, individually room by room. The RAS-B2 is a 2-in-1 temperature control and automatic balancing valve, combining a thermostatic radiator valve and pressure controller for two-pipe heating systems.

www.danfoss.com

 

[big john hog]

Problem radiator now getting hot

Dear Shaun problem rad now scalding hot boiler on 3 I think that this is the best we can get.Maybe some rads to big for 10 mm pipe work so pump may be winding down slightly from ten years of some days sixteen hours a day running

 

[big john hog]

Fully hot / acceptable?

You either have a balancing problem or pump is weak

Shaun my thoughts exactly .I have tried every balancing trick under the sun same result.My plumber is going to replace the old eleven year old grundfoss with the new ups3 .I wonder if the speeds on this are higher rpms My neighbor has just had one fitted and his is only on speed setting one and he says the rads are getting hotter quicker. Do you know if the latest ups3 is powerfull enough for five /six bedroom house .Maybe thats the one I need .Again many thanks for your expert advice.

 

[ShaunCorbs]

Is your neighbours roughly the same size and layout as yours ?

 

[big john hog]

Is your neighbours roughly the same size and layout as yours ?

Actually Shaun his house is bigger and he has had boiler replaced but before new pump installed .He said to me today that the pump made the biggest performance improvement over the boiler.

 

[ShaunCorbs]

I would question speed 1 more like speed 3

 

[big john hog]

I would question speed 1 more like speed 3

Yes I totally agree with you Shaun more like speed three.Just one more question I remember many years ago when we first moved in ,of the fourteen radiators five were upgraded .three singles to doubles but of the same size i.e length and height but two chrome towel radiators in bathrooms from normal size radiators .Does doing this mean that the pump should have been switched from speed two to three its the standard domestic grundfoss super selectric 15/60 130 .Also Shaun I can remember the plumber having to come back every three years approximately and having to flush the boiler as it would be kettling May be the system was under inhibited as I noticed he would only put one bottle of inhibitor in the system. If I had the pump speed to low on setting two as you are always told to set it at that speed Maybe I should have set it to speed three all those years ago .When I eventually have the pump replaced I will let you Know the results.The plumber agreed with me that the system has slowed down in the heating process .It must be the pump Shaun as this circulates the heated water from the boiler.Also Shaun on the non lock shield valves I have all trv valves fully open and control temperature on the room thermostat. I have all the wheel head valves fully open. The three downstairs and one on the landing upstairs take approximately two and a half turns to be fully open but the two wheel head valves on the chrome towel radiators upstairs in the bathrooms are also fully open at five full turns .Have I set the non lock shield valves correctly or am I wrong in having them fully open.

 

[big john hog]

Yes I totally agree with you Shaun more like speed three.Just one more question I remember many years ago when we first moved in ,of the fourteen radiators five were upgraded .three singles to doubles but of the same size i.e length and height but two chrome towel radiators in bathrooms from normal size radiators .Does doing this mean that the pump should have been switched from speed two to three its the standard domestic grundfoss super selectric 15/60 130 .Also Shaun I can remember the plumber having to come back every three years approximately and having to flush the boiler as it would be kettling May be the system was under inhibited as I noticed he would only put one bottle of inhibitor in the system. If I had the pump speed to low on setting two as you are always told to set it at that speed Maybe I should have set it to speed three all those years ago .When I eventually have the pump replaced I will let you Know the results.The plumber agreed with me that the system has slowed down in the heating process .It must be the pump Shaun as this circulates the heated water from the boiler.Also Shaun on the non lock shield valves I have all trv valves fully open and control temperature on the room thermostat. I have all the wheel head valves fully open. The three downstairs and one on the landing upstairs take approximately two and a half turns to be fully open but the two wheel head valves on the chrome towel radiators upstairs in the bathrooms are also fully open at five full turns .Have I set the non lock shield valves correctly or am I wrong in having them fully open.

 

[ShaunCorbs]

It’s not a ups2 ? It’s older than 10years then

Depends if it’s a sealed system but normally open vent can pump over on speed 3

 

[big john hog]

It’s not a ups2 ? It’s older than 10years then

Depends if it’s a sealed system but normally open vent can pump over on speed 3

Yes that's correct Shaun the pump has no green leds the model before ups2 just the old manual side lever fitted approximately April 2010 .The system has f.e. tank in loft so open vent system.

 

[ShaunCorbs]

I would have a look in the loft when it’s on speed 3 make sure it’s not coming back over via the vent