Strange heating issue

[Wallsy]

Hi All,

I've re-attached two radiators back to the system after some decorating and I now have the problem where I get heating upstairs but very little heating downstairs to none on some. Followed various tips such as balancing (all rads (4 in total) upstairs are only set to 1/4 turn open on lockshield) and then downstairs are set as 1/4, 1/2, 3/4, 1 turn as I think they are distance wise from the boiler. I have fully drained the system twice and during the second drain replaced the pump on the boiler (WorcesterBosch Greenstar 241 Junior) thinking that the pump was failing.

All rads are bled so I do not think there are any airlocks in the rads so could the problem be in the main pipework supplying the downstairs rads??? Or could there be a blockage somewhere. System was powerflushed ~7 years ago when all rads replaced. All water coming from rads is clear and inhibitor has been used throughout the duration I have looked after the system.

Any help is appreciated.

 

[terryplumb]

Turn all upstairs rads off by their trv or wheel head valve ( not their lock shields). See if this results in all downstairs rads getting to Temperature. Sounds like you have not balanced the system.

 

[Wallsy]

Before I do this why via the TRV's? wouldn't shutting off via the lockshields be the right way to do this as that shuts the flow of water off to the rad completely without having the TRV open if the temp drops?

 

[SFK]

Wallsy,

If you switch off the lockshields then you have changed the balancing that the locksheild was set to, adding an extra variable and extra work when you also have to then rebalance them.

By only switching off at the TRV, you can easily reinstate the TRV (and radiator) at their original setting.

Note that it does not matter which side of a radiator you turn them off at. Whichever side is turned off, stops the flow of water through that radiator and so radiator still gets cold.

SFK

 

[Wallsy]

SFK,

If I adjust the TRV doesn't that affect the point at which the TRV kicks in when if set to a lower number will close the valve at a much lower room ambient temperature? I understand that the idea of balancing is to ensure that the flow to the radiator is sufficient to get it to temperature and get the room warm. However if all the upstairs lockshields are set to 1/4 turn open that doesn't leave me much in the way of adjustment to further restrict the flow down to those if downstairs requires more. As you said it doesn't matter which end is adjusted as either side will restrict the flow.

 

[terryplumb]

The lockshield is used to balance the system upon commissioning and thereafter gets left alone ( unless for instance you want to remove the rad ) the trv is for the householder to use to set temperature as desired as often as desired. As the water getting pumped around your radiators will take the path of least resistance ,the LS valve is used to create resistance ,at each rad ,so every rad gets the same ,hence balanced.

 

[SFK]

Walley,
Terry was suggesting that you "Turn all upstairs rads off by their trv (not their lock shields) and monitor if all downstairs rads get to Temperature" as a quick experiment to see of there is a balancing issue or a blockage issue.
If you did this experiment using the Lock Shields (ie Turning off all upstairs rads off by their lock shields), then it will not be a quick experiment as you will then have to re balance all the Lock Shields whatever the outcome.
SFK

 

[Wallsy]

OK. All TRV's turned off on upstairs rads and no heating downstairs. Inlet pipes up to rad are warm / hot but nothing going into the rad. Boiler kicks in to heat water but after about 30secs to 1 min shutsdown. No warning lights on the boiler at all. One of the rads was removed yesterday and flushed with a hose using mains pressure water and all clear in terms of water coming out. I banged the rad to see if anything was stuck / lodged but no joy. Is it possible I just have an airlock on the return to the boiler that is difficult to shift???

 

[terryplumb]

You have a combi boiler ,and you have replaced the pump ,i think you said early on ( havent re read all earlier posts ,so correct me if i am wrong)
Is the pump spinning ,have you bled the pump, does your boiler have an auto bleed valve and is it open ?
When you removed one rad ,did you open the valves to ensure water flows from them ( to rule out blockage / obstruction ) ? If you turn off the trv on ALL rads except one that wont heat,
leaving both its valves fully open, does that rad then heat ?
Is your domestic hot water from taps EXCESSIVELY hot ?