Solution to one stone-cold Radiator

[chrisb2]

Just had a new boiler (Vaillant ECO TECH PLUS 418) and hot water cylinder. This heats both the hot water and central heating system.
One of the rads remains cold upstairs in one of the two loft bedrooms. Been told that an "expansion vessel" should cure the problem as this should provide added pressure.
Comments as to the validity of this and whether there are any other solutions if this is not appropriate.
Many thanks.

 

[landyandy]

Have you tried balancing your system?

http://www.diydata.com/projects/centralheating/balancing/radiator_balancing.php

Andy

 

[weargas]

Been told that an "expansion vessel" should cure the problem as this should provide added pressure

Complete shyte. An expansion vessel doesn't add pressure it absorbs the expansion, sounds like someone's trying to have your pants down.
Try what landy said but also is it an existing radiator?? Has it got a thermostatic valve on?? If it has it could just be stuck in the closed position (even though the head turns the pin underneath remains stuck down keeping it off)

 

[chrisb2]

Thanks for the replies.
It is an existing radiator that was working the day before, after the new boiler was fitted on the same day.
However, the pipes leading into the rad' from both sides remain stone cold, so the hot water for this radiator is not even getting this far.
The rad' is bled but only cold water coming out.
Any further suggestions please.
Thank you.

 

[landyandy]

As said before, you probably need to balance the system.

Try turning some of the other rads off. Then check if this problem rad is getting hot.

Andy.

 

[mickyg]

Was the boiler moved and was any additional pipework done?

 

[chrisb2]

Thanks.
Will do as you suggested and balance the system, but first I will turn off some of the Rads' off to see if that solves the problem which will of course create another one with those turned off.
No, the boiler is in its original position...........wall mounted behind a cupboard in the kitchen, with an extended vertical flue now as original flue was between the top side of a conservatory roof and the next doors wall !!!
I must say the recommended corgi plumber has done an excellent job......about £1500.00 cheaper than British Gas who were going to move the boiler and create upheaval upstairs in our mid-terraced property.............nightmare !!!
Items replaced were some of the existing pipework, water pump, hot water cylinder with electric emersion heater now switched off, some rads now have thermostatic rad' valves and where any leaking rad' valves were replaced with "normal" valves.

 

[bengasman]

Just had a new boiler (Vaillant ECO TECH PLUS 418) and hot water cylinder.

One of the rads remains cold upstairs in one of the two loft bedrooms. Been told that an "expansion vessel" should cure the problem as this should provide added pressure.

total nonsense, get the installer back to do the job properly

 

[mickyg]

It is an existing radiator that was working the day before

this is what made me ask the question I did, could just be an airlock perhaps, but I would be inclined to agree with Ben, get your installer to check it.

 

[chrisb2]

Suggestions and solutions please to this problem if possible........
Rad' in loft now working....sticking thermo'valve.

However, when the CH & the HW are on at the same time, 4 of the upstairs rads either go cold or lukewarm even though the thermostat controlling the CH Temp' is fairly high.
Downstairs rads' are not affected and stay hot.
But when the HW is switched off for the HW Cylinder tank, this cures the problem of the cold rads' and they get hot upstairs.

I need BOTH the CH & HW to work simultaneously.

Possible solutions please.
Thank you.

 

[mogget]

It sounds like it needs a gate valve somewhere on the hot water circuit so it can be balanced along with the radiatiors.

If the hot water circuit is in 22mm with no balancing valve then it will 'steal' water from the radiator circuit as the water will naturally take the path of least resistance.

 

[chrisb2]

Many thanks Mogget.
I'll suggest that solution to my plumber who is coming tomorrow.
I'll let you know what he says.

 

[chrisb2]

Problem solved...........
The 30 year old open system with hot water cylinder/CH was reliant on gravity apparently, and where the new Vaillant boiler and system does not. The problem stemmed from a return valve left over from the old system and hidden under the stairs which has now been removed and replaced by new pipework.
CH & HW are now functioning together with the hot water circulating much more freely.
Just thought I would let you know.

 

[chrisb2]

Premature solution and still have problems.
After the removal of the non-return valve from the old gravity system, which used the 30 year old Potterton Netaheat MKII 16-22 (now replaced with Vaillant ECO TECH PLUS 418) the HW and CH will now work together, whereas previously they did not.

New problem: when CH goes OFF at night and where HW is set to stay on permanently via the programmer, the rads go mostly OFF both downstairs and in the two loft bedrooms. However, the mid section consisting of two bedrooms and a bathroom, the rads stay ON when of course they shouldn't be.
With this scenario I used 1.4 cu ft of gas overnight just to keep the HW tank at its tank-thermostat controlled temp' of 60C.
Ideas anyone?
Seems like I am using MORE gas NOW than BEFORE with this A rated energy saving boiler.

 

[jackthom]

Try turning the CH OFF and with demand for DHW ON, check that the

Untitled

• jackthom
• 19 Dec 2008
• 18

mid-position valve is right back in the Domestic Hot Water only position.

Hot water enters the valve shown in the picture via the middle (vertical) connection and only the exit leading to the DHW cylinder should get hot.

If the CH circuit also gets hot you will have to check the wiring to the valve but beware of the mains voltages involved.

For DHW ONLY, both the white and grey wires should NOT be LIVE.

If the voltages seem correct but hot water is still circulating through both circuits try manually moving the valve position a few times in the hope this will free things up a bit.