Heat Exchanger Plate

[rsg444]

Hi there, I have a Glow Worm Easicom 28 (not by choice). For the third time now my hot water temperature fluctuates, the first time it happened I had an engineer come over who done a complete power flush and said the water was actually quite clean, in fact when I was watching the water coming out, it was clear. He went around knocking the radiators with a rubber hammer and at best some black flakes come out during the flush.

He also checked the magnetic filter and although it had some black deposits, again he said it was pretty clean. Anyway, he took the plate off, put some acid into it and loads of black deposits came out which done the trick. Four months later we got the same problem. This time a Vaillant engineer came, looked at the magnetic filter and said water was clean with minimal deposits. He changed the plate for a brand new one and put in a new pump. He showed me the old plate and it was full of black deposits. This worked fine for over a year until last week, it happened again.

Had the engineer over again, he again looked at the filter and the water he had to drain and said that the system is clean. He took the heat exchanger plate out and showed me black deposits in there, he's cleaned it with acid and our hot water is fine again.

The question is, if my water is clear, I have a magnetic cleaner in there, where is this stuff coming from? Heating system has inhibitor in there, it was tested last week and showed to be adequate.

Any advice would be appreciated.

 

[terryplumb]

Is the filter fitted to the Flow ? If so the water and it's contaminants will flow through the boiler before reaching the filter.

 

[rsg444]

When you say flow, I'm assuming you're referring to outward (in layman speak)? The filter is installed at the return - at least none of the engineers have said it's been installed incorrectly.

 

[terryplumb]

When you say flow, I'm assuming you're referring to outward (in layman speak)? The filter is installed at the return - at least none of the engineers have said it's been installed incorrectly.

Yes the flow brings heated water from boiler ,return brings it back.

 

[rsg444]

Though a bit of additional information, when we moved into our home, the boiler was only 6 months old - however when we changed the old radiators for new ones, the water that came out of the heating system was like treacle. The guy who done the work was astounded and said that it looks like whoever installed the boiler didn't even bother flushing the system. So we flushed it all out, installed new radiators all around - is it possible its stuff from before the flush within the boiler?

 

[terryplumb]

Possible I suppose ,but rather unlikely. What is the timescale from boiler install,to new rads and flush ? And time spans in between HEX being blocked , cleaned,and blocking again. ?

 

[rsg444]

Boiler installed by previous owner of house in February 2015.
New radiators and system flush when I bought house in September 2015.
November 2018 Hot water started fluctuating, power flush done and HEX cleaned with acid.
March 2019 Hot water started fluctuating, HEX replaced and Pump replaced
May 2020 Hot water fluctuating, HEX cleaned with acid.

 

[terryplumb]

It would appear that the flushing hasn't been very successful. That's fairly rapid re occurrence of the PlateHex blocking ,on a system that has been powerflushed ,and new radiators fitted.

 

[dilalio]

What magnetic filter do you have?

 

[hard-work]

Best have a magnetic filter with incorporated solids filtration as well. Black deposits can mean plastic/rubber parts of the system are disintegrating. I have known that on the expansion vessel's rubber. Not ferrous so a magnet will not pick it up.

 

[rsg444]

What magnetic filter do you have?

Hi there, I have Trappex Centramag

 

[rsg444]

Best have a magnetic filter with incorporated solids filtration as well. Black deposits can mean plastic/rubber parts of the system are disintegrating. I have known that on the expansion vessel's rubber. Not ferrous so a magnet will not pick it up.

Can you recommend anything?

 

[rsg444]

It would appear that the flushing hasn't been very successful. That's fairly rapid re occurrence of the PlateHex blocking ,on a system that has been powerflushed ,and new radiators fitted.

But everyone who comes to repair this say that the water looks clean.

 

[ScottishGasMan]

It doesn't really matter what the water looks like. the fact is you have black flakes building up inside the boiler, and there are highly likely to be magnetite. Therefore the flushing has not been successful so far.

Is there any chance some of your radiators are fed via microbore pipe (pipes with a diameter of 8 or 10mm)?

Magnetic filters while somewhat helpful are in no way a solution to contaminated water.

For further advice we would need to know the size of pipes to the radiators, if they go under the floors or are "drop fed" from above, when it was powerflushed what chemicals were left in afterwards inhibitor wise?

 

[rsg444]

It doesn't really matter what the water looks like. the fact is you have black flakes building up inside the boiler, and there are highly likely to be magnetite. Therefore the flushing has not been successful so far.

Is there any chance some of your radiators are fed via microbore pipe (pipes with a diameter of 8 or 10mm)?

Magnetic filters while somewhat helpful are in no way a solution to contaminated water.

For further advice we would need to know the size of pipes to the radiators, if they go under the floors or are "drop fed" from above, when it was powerflushed what chemicals were left in afterwards inhibitor wise?

Hi, all of our radiators were replaced and all are using 15mm pipes that come in from the bottom.

After the power flush it was treated with Sentinel X100 Inhibitor.