Boiler cleaner and inhibitor

[britishboy7]

I need to flush through our Worcester Bosch Greenstar 30i combi boiler (it’s been 2 years since last cleaned) and will use the Magnaclean 2 filter to add the fluids.
Going to clean the Magnaclean first. What’s the best cleaner and inhibitor to use? Furnox, Adey or Sentinel?
And I’ve got 2 underfloor heating circuits too, should I leave those both fully open when carrying out the clean and adding the inhibitor?
Thanks all

 

[Mottie]

Surely if it’s a sealed system with inhibitor and a magnaclean, it shouldn't need flushing after 2 years?

 

[Harry Bloomfield]

I need to flush through our Worcester Bosch Greenstar 30i combi boiler (it’s been 2 years since last cleaned) and will use the Magnaclean 2 filter to add the fluids.

Cleaning, should only needed, when a system has been neglected in the past. If it was cleaned properly, just two years ago, and inhibitor added, then it shouldn't need it now.

 

[spile]

I use Sentinel x100 and add it through the Adey Magnaclean filter. Drain what’s in there with a tube. Add as most of the bottle and refit. Add the rest a day or two later.

 

[britishboy7]

Thanks guys. I did it 2 years ago as the hot water was pulsing when running, flow rate would increase then decrease every 10 or 15 seconds. Colleague at work said the heat exchanger could be clogged up. Was fine after the flush previously, but maybe hadn’t been cleaned for 4 or 5 years previously. Also had a couple of radiators off and back on in that time.

Just checked this morning as I bled the radiators yesterday afternoon (3 upstairs had air in) and refilled the boiler via the filling loop to a little over 1 bar. This morning the gauge is sat at about 1/2 bar. Any suggestions what to check before I call an engineer out?

 

[Mottie]

Just checked this morning as I bled the radiators yesterday afternoon (3 upstairs had air in) and refilled the boiler via the filling loop to a little over 1 bar. This morning the gauge is sat at about 1/2 bar. Any suggestions what to check before I call an engineer out?

Maybe the pressure has dropped as the system has cooled and the water contracted. Bleed it and top up again while cold. Had it been losing pressure by that amount before you bled and topped up the system?

 

[britishboy7]

Thanks again Mottie
I hadn’t checked the pressure for a few weeks prior to topping up the system yesterday, and when cool it was about 1/4 bar. Topped it up to 1 1/4 bar, bled it then topped up again to 1 1/4 bar. It’s been on this morning so once it’s cooled I’ll repeat and report back.

Does the heat exchanger getting clogged up/ reducing flow every couple of years sound right? Was a definite improvement in flow 2 years ago when I ran Sentinel x800 through the system. We are i hard water area (if that makes any difference)

 

[Harry Bloomfield]

Does the heat exchanger getting clogged up/ reducing flow every couple of years sound right? Was a definite improvement in flow 2 years ago when I ran Sentinel x800 through the system. We are i hard water area (if that makes any difference)

It doesn't sound right, you need to investigate why the HE is getting clogged. Hard water should make little, or no difference - unless you are having to constantly replenish the water, or keep draining and refilling.

My system was put in, in 1985-ish. It is on it's third boiler, 2nd pump (1st was replaced, despite being OK), 2nd 3-port (had to be replaced, to match different type of head), and numerous actuator heads. During that time, it has never needed flushing, or cleaning, though it has been completely drained down twice. When drained, the water comes out, perfectly clear and zero debris. At the last boiler swap, a Magnaclean was added as a precaution, in the return. I've checked the Magna a couple of times since fitted, and there was nowt in it.

All it has needed is the inhibitor checked, and the level maintained. Each time it is drained, and refilled, a fresh lot of air and oxygen is introduced into the system.

 

[livingstoned]

Does the heat exchanger getting clogged up/ reducing flow every couple of years sound right?

Not unless your water is extremely hard, which doesn't apply in many places.
If you take the secondary heat exchanger out , it will tell you a lot. If the primary side is limescaled, which is unusual, that could reduce flow. If the secondary side is clogged with black magnetite sludge, that would reduce the hot water temperature and cause the temperature to be unstable. Citric acid from the supermarket will deal with both.

The boiler will have a flow restrictor somewhere, which is often a piddly little O ring on a plastic carrier, something like this:

Those can block , fall apart etc. The manual should tell you where it is.