- Joined
- 2 Mar 2006
- Messages
- 47
- Reaction score
- 0
- Country
Old CH system and always had problems with one rad not getting hot. Flushed the system today and did a sort of bucket test on both ends of the pipes feeding the suspect rad... no problems. Flushed rad, a bit of gunge.Normal valve one end, TRV the other ok.
Put it all back together and left only suspect rad valves open and pump on highest speed setting.... doesn't heat up. Opened the valves on the other 3 rads in the downstairs circuit one at a time and they are scorchio. Some head scratching. Closed the return valve on the rad and with the TRV fully open I opened the bleed valve... seemed to have full pressure ( gravity fed) and after bleeding 1/2 a bowl full I was getting warm water and the pipe below the trv was hot....hmmmm. Opened the return valve and it still doesn't get hot.
So I go into the basement to inspect the flow/return layout. The hottest pipe I reckon is the flow from a temp test on the pipes on the other rads.
The suspect rad is fed off a tee . One other rad on the same downstairs circuit is fed off a tee and that gets hot ok. What seems to be the problem is that the tee does not come off horizontally... it is about 25degrees below the horizontal so the pipe drops about 5 inches before turning vertical to go into the TRV.
......................TRV
.......................¦
T-._.................¦
.......-.._...........¦
..............-..._...¦
.....................-.¦ not to scale !
I can't imagine why the installer dropped the pipe rather than go horizontal. As I have flushed there shouldn't be any gunge in the below horizontal bit of the pipe to stop flow. The pipe at the tee is hot but drops to cold just a few inches along the 15inch run, so the water is clearly not flowing downhill
Can anyone confirm that the water would not like flowing downhill and thats the reason for the rad not getting hot or have I got a weird TRV ? The bleed test would suggest the TRV is letting water flow.
Put it all back together and left only suspect rad valves open and pump on highest speed setting.... doesn't heat up. Opened the valves on the other 3 rads in the downstairs circuit one at a time and they are scorchio. Some head scratching. Closed the return valve on the rad and with the TRV fully open I opened the bleed valve... seemed to have full pressure ( gravity fed) and after bleeding 1/2 a bowl full I was getting warm water and the pipe below the trv was hot....hmmmm. Opened the return valve and it still doesn't get hot.
So I go into the basement to inspect the flow/return layout. The hottest pipe I reckon is the flow from a temp test on the pipes on the other rads.
The suspect rad is fed off a tee . One other rad on the same downstairs circuit is fed off a tee and that gets hot ok. What seems to be the problem is that the tee does not come off horizontally... it is about 25degrees below the horizontal so the pipe drops about 5 inches before turning vertical to go into the TRV.
......................TRV
.......................¦
T-._.................¦
.......-.._...........¦
..............-..._...¦
.....................-.¦ not to scale !
I can't imagine why the installer dropped the pipe rather than go horizontal. As I have flushed there shouldn't be any gunge in the below horizontal bit of the pipe to stop flow. The pipe at the tee is hot but drops to cold just a few inches along the 15inch run, so the water is clearly not flowing downhill
Can anyone confirm that the water would not like flowing downhill and thats the reason for the rad not getting hot or have I got a weird TRV ? The bleed test would suggest the TRV is letting water flow.