Radiator not getting hot

[JohnD]

what were the results when you balanced the system?

is there a bypass?

 

[merton69]

I did the LS process you asked about some weeks ago (see previous replies) and now the whole system takes ages to warm.

Which is why the pump has been looked at and now the air lock is the next possibility.

 

[JohnD]

is there a bypass?

 

[merton69]

Sorry......I don't know what a bypass is?

 

[JohnD]

BYPASS: pipe linking the flow and return of a boiler used as a means of dissipating exess heat(also see auto bypass)

...It is also possible that your system has a bypass pipe fitted to allow circulation even if all the rads are turned off, as might happen if you have TRVs on all rads and no room stat. In this case you will find the flow and return pipes at the boiler are both very hot, and all the rads are cold, so you have to follow the pipes until you find the bypass connecting hot and cold. It may have an adjusting valve on it but should never be fully closed...

You haven't got a hot-water cylinder, or an always-on towel rail, have you?

One cause of a system which gets less efficient with age, is sludge or sediment accumulating in the pipes and radiators. Cleaning chemicals such as Sentinel X400 will loosen this. You will know it is working when the circulating water goes jet black with loosened sediment (visible at the bleed valves)

To speed up circulation, you can gradually open the LS valves, a tiny fraction of a turn at a time, starting with the rads most in need of extra heat. As soon as other rads go cold, you know you have gone too far, so tighten it down again until flow is equally shared by all radiators.

 

[merton69]

When you say follow, do you mean turn on the heating so the pipes are warm and feel from the boiler to where they are both hot?

I will have a look tomorrow. Again, a similar question to one I have already asked....why should I be adjusting a valve, when it hasn't been adjusted ever before?

We have TRVs on all the rads except the hallway. No room stat, just the one on the boiler, (see image in another reply).

What I do know is the two pipes that coming down in the hallway (from upstairs) to feed the single rad (with no LS) and the double rad in the living room (see floor plan in other reply), one is hot and the other is cold.

 

[JohnD]

if the Return pipe is hotter than the radiators, follow it back to see where it is getting the heat from.

if something has changed, it might be that someone has altered things, or it might be that there is a blockage or restriction, most likely caused by sludge or sediment. This develops over time.

 

[merton69]

This is what I have been querying all along. Nobody has been in to adjust anything.....

...the only person to adjust anything since the installation is me and that is the annual bleed of the radiators and nothing else. No adjustment to the TVRs or LS's....until now of course.

 

[JohnD]

most likely caused by ...

 

[merton69]

...and that means what exactly?

 

[JohnD]

it's to remind you of what I said before but you ignored

"it might be that there is a blockage or restriction, most likely caused by sludge or sediment."

 

[merton69]

...which is what I partly diagnosed from the beginning.

I haven't ignored yours or anyone's else valued opinion...just questioned them so I can learn from all the knowledge coming my way.

I simply was asking why adjust the LS, valves etc when they weren't touched since the install, which says to me it's something like a blockage!

As said before...I do appreciate your knowledge.

 

[merton69]

I have now drained and installed a drain off cock under the downstairs double rad.

I then flushed through the system, re-pressurised and then turned it on.

And still the downstairs rads struggle to get heat through them!

Today, I turned off all the upstairs rads and turned on the CH only to find the downstairs rads do get warm but nowhere near the temp the flow to pipe is and still takes ages to do so.

I have also noticed that the boiler when switched on for the first time, you can hear the pump whirring and the gas lighting. This only goes on for about 15 seconds, then goes off but the pump continues to whir. This doesn't seem to lie well with me as I am sure the boiler would go on longer for more than approx. 15 seconds.

I do not know what to do next?

My wife has also just reminded me that back in September we had an Gas mate to replace the diaphram on the hot water feed.......would this effect anything please?

 

[merton69]

Sorry, but I forgot to ask on how to find out if the pump is fully working please?

And is there two pumps, one for the water feed and one for the CH or is it only one to do both?

 

[merton69]

..As far as I can see, there is not a bypass.

Tasks done so far:-

• Flushed out radiators.
• Flushed out system at least 3 times.
• Checked the TVR's.
• Done the LS process.
• Added another drain off cock and flushed system.
• Removed pump, cleaned and re-installed.

And still the double rad is very very slow in getting hot.

Once again, I do appreciate all your advice so far!