Renewing rad TRVs in a Boilermate 2 system

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Renewing rad TRVs in a Boilermate 2 system

Post  GreasyPop on Tue Aug 08, 2017 8:39 am

Hi. I have been doing my own plumbing (apart from the gas...) for over 40 years, but had not encountered a Boilermate until my daughter and her husband bought a house with this system. System itself works well, but unfortunately some of the TRVs on the rads are showing their age and need replacing. Would closing the CH pump isolator valves isolate the CH flow from the heat store, or will I have to drain down the entire tank? As I would only be renewing the TRVs (on the flow side), closing the lockshield valve on each rad should shut off the return...

Many thanks.

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Re: Renewing rad TRVs in a Boilermate 2 system

Post  mike on Thu Aug 10, 2017 2:42 am

It would be better to;
1; Drain water and check unit takes water from top tank.
2; If it does then drain down unit and system.
3; Fit new TRV's and lock shields to if signs of leaking etc
4; If water is brown (sludge) Put in cleaner and run for a period of time.
5; Drain again when hot
6; Add inhibitor 1 bottle for every 10 rads / 100 litres don't forget the thermals store too 150 litres would be 1.5 bottles.
But check the size of yours. Could be 150, 180, 200 etc.

Mike
MGC/H2O
Norfolk

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Re: Renewing rad TRVs in a Boilermate 2 system

Post  GreasyPop on Thu Aug 10, 2017 7:00 am

Thanks for your advice Mike. Given the age of the system (about 14 years) a drain and flush would probably not be a bad idea. I was intending to add Fernox or Sentinel in any case, and would have checked the feed from the F & E jockey tank as I have known these to block. Are you aware of any problems that can occur specifically with Boilermates when refilling (airlocks etc), or do you have any tips I should be aware of?
I have noticed that all the lockshield valves are fully open - as the return is simply circulating to the thermal store and not directly back into the boiler, presumably there is no need to have a temperature drop across the radiators? All rads get hot, so the system doesn't seem to need balancing.
Much obliged.

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Re: Renewing rad TRVs in a Boilermate 2 system

Post  mike on Thu Aug 10, 2017 9:25 am

Do it in the order I stated.
Number 1 is most important.
Check unit will take water from the top tank which may be on top of the unit.
Or fitted else where (loft)
Check that the unit vent is ok too.
If blocked and you drain the unit. It will implode upon itself.
After that carry on.
Any system needs balancing. Any rad getting hot very quickly can be nipped down on the lock shield.
There will always be some rads get really hot first. Others much later.
With a thermal store because the unit may be fully heated (unless DHW has been used eg bath)
Then the heat is ready to be pumped around the rads, rather that waiting for the boiler to heat the water as per a normal system.
One of the benefits of a thermal store. Will heat the house quicker.
Another thing boiler needs to be on MAX

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Re: Renewing rad TRVs in a Boilermate 2 system

Post  GreasyPop on Fri Aug 11, 2017 4:12 am

Hi Mike,
F&E tank is just above the unit, very difficult to see into. However, I guess if I start to drain down, if water is flowing from the tank OK I should hear the ballcock valve open pretty soon. There's a service valve to the ballcock so I can then close it quickly.
More worrying is your comment about the unit vent - where on the unit is this vent located? Does it just vent to the jockey tank like a conventional gravity system? (my daughter's house is 45 minutes away so I can't look right now!!).
I completely agree about balancing. I'll start from cold and nip down any rads that appear to be getting hot too far ahead of the others. And I'll check the boiler is on max ;-)

Many thanks.

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