Hot Rads upstairs OR downstairs but not both together. Help

[SE82]

Hello,

We have a Baxi duo tech 40 HE and two weeks ago we noticed that one of our downstairs rads was cold, the next day we lost heat from two more in the lounge. This continued until we lost 6 radiators downstairs.

We had our whole system balanced in January and managed to get our kitchen rad working which hasn’t worked for years.

A plumber suggested an airlock or new pump so left me with instructions on how to try and clear the airlock and a quote for the pump. His other suggestion was a chemical flush.

This is what I’ve done so far

• Turned all rads off and the furthest rad upstairs on full, waited for it to get hot then moved to the next. Only 2 got hot so I….
• Changed the pump head
• Cleaned the magna clean
• Then the boiler kept losing pressure so changed the pressure release valve
• Disconnected one rad downstairs to check if the flow was full of gunk but the water was totally clear.
  
• Since the new pump I can get 5 rads upstairs lukewarm. 2 remains cold.
• Or I can 1 rads hot and 5 cold downstairs. I have to turn all the rads off upstairs or downstairs to get heat in the other.
  
• I’ve tried to release a possible airlock following the new pump installation and bled the rads.

Do I need to try a different way of removing the airlock? Or rebalance the rads?

 

[cross thread]

They have a filter in the return valve, try clean it out

 

[SE82]

They have a filter in the return valve, try clean it out

Thanks.
That sounds difficult to access…. Would I need to just do it on the cold rads? Or the lukewarm ones too?

 

[cross thread]

Return valve is on the boiler,it has a cap on the valve once drained can be removed

 

[SE82]

Return valve is on the boiler,it has a cap on the valve once drained can be removed

Thank you! It was a bit more involved as I had to take the filling loop off. The metal gauze was completely rusted to the inside. After some wd40 and tugging i eventually removed it and cleaned off all the rust.
The great news is the rads all started working immediately and just needed balancing again.

Now I’m wondering if I need to do a chemical flush if it was that rusty in the return valve?

 

[SE82]

Hi, reopening this as we‘re back in a similar situation.
I think it has probably furred up the gauze inside again (I didn’t add any inhibitor) and I want to do a chemical flush on the system. We have a magnaclean and I have the following questions:
*which of the many chemicals are recommended?
*can I add into the magna clean rather than siphoning water out of the one of the rads?
*do I need to fully open all the trv’s and lock shields?

 

[Deleted member 267285]

Sentinel/fernox/Adey for chemicals, yes it can be added via magnaclean, but ensure enough water has been emptied - perhaps drain at the boiler too? Yes open all valves, unless you only want certain rads cleaned?

 

[SE82]

Sentinel/fernox/Adey for chemicals, yes it can be added via magnaclean, but ensure enough water has been emptied - perhaps drain at the boiler too? Yes open all valves, unless you only want certain rads cleaned?

Thanks for speedy reply.
Which brand of chemical is best? I plan to leave it in for a few days/weeks and then drain down rather than panic about using x800.
Happy to drain down boiler to get more in. From looking at the guidelines I need a lot of the stuff for our 16 double rads so probably quicker to add to the rad.

 

[Deleted member 267285]

Everyone’s opinion is different, so can’t say which is best but any of those 3 is fine.

 

[Jackrae]

If you have a towel rail with a blanking cap at the top you can syphon water from it to make 'space' for adding the chemical into the towel rail. The chemical will then circulate through the complete system if all radiator valves are open.

 

[Johntheo5]

Just a word of caution re chemical clean, ensure that the system is thoroughly flushed out a number of times after chemical cleaning. There are numerous cases of problems. Hydrogen gases forming etc, some actually blame the inhibitor reacting with the now cleaned system, personally I would prefer to keep cleaning the filter, maybe add some inhibitor each time until the filter runs clear but there again there are probably hundreds of happy people who do a chemical clean.

 

[SE82]

Just a word of caution re chemical clean, ensure that the system is thoroughly flushed out a number of times after chemical cleaning. There are numerous cases of problems. Hydrogen gases forming etc, some actually blame the inhibitor reacting with the now cleaned system, personally I would prefer to keep cleaning the filter, maybe add some inhibitor each time until the filter runs clear but there again there are probably hundreds of happy people who do a chemical clean.

Thank you. Very good tips.
I have never done a flush before but I have completely drained the system before. I need to read up…. If you have any advice or helpful tips please share.