Heat Exchanger keeps blocking up

[mattysupra]

Hi, i have a Vizo boiler. It around 7 years old now at guess.

Problem is every 6 months the heat exchanger keeps blocking and the water goes hot and cold. I kept having them replaced but for the last couple of years i have been removing and cleaning every time it blocks. Yes im now doing it myself (the removing and cleaning as got feed up of paying someone to keep putting a new part in), i know i shouldnt be messing myself before anyone says but it doesn't involve opening up the burner section of the boiler. I would never dream of messing in there.

I cant and the other boiler techs i have had in cant work out why it keeps doing it.

It gets blocked up with a black hard like carbon material i have to tap the heat exchanger with a rubber mallet to loosen and remove.

In my battle to combat this issue i have done the following-

2x powerflushes
New radiators
Drain + clean every 12 months
Inhibitor (different brands tried)
Fernox TF1 filter (i clean this out every 3 months and its always full of crap)
The boiler has been relocated after a extension
The house has been rewired (it was suggested that a wiring issue touching pipes might be a cause so when i had extension all electrics was also upgraded)
All extension pipework is plastic, original is copper.

Why does this keep happening the boiler does not loose pressure either? I had considered changing teh boiler to a better brand but will this stop the issue?Is it the boiler causing this?

thanks in advance .

 

[gasanstuff]

Powerflush required.
Not been done properly maybe?
How was it powerflushed before?

 

[DP]

Could be the plastic pipe.

If the filter is full of sediment, why clean it at three months and not much sooner. The purpose of installing this unit is to catch the muck before it enters the boiler. If it is full at three months, then it has not been very effective as it is full and now the muck is entering the boiler and blocking up the filter. Catch it before the the muck starts moving into your boiler

Stop emptying your system also. Each time you fill your system, fresh water that is put in the system will have air in it that will be react with system components to produce black muck you are trying to get rid of. One thorough cleanse and treatment is all that is needed

 

[AlexCarp]

I read in old threads that putting in a plate heat exchanger and another pump solves the problem as the boiler water only pumps around the plate heat exchanger and does not come in contact with the water in the radiators. I suppose a good idea for any expensive boiler.

I agree at not draining the system every year is a good thing as it introduces oxygen. If the power flush was not that successful, how about cleaning the filter and inserting X-900 which loosens the crap in the system and the filter catches it. You may have to empty the filter every few days until none is in the system. I asked here for feedback from anyone who has used X-900. I got none, but Sentinel are a good company so worth a try.

 

[AlexCarp]

I just did s search and some positive feedback on this thread on X900...
//www.diynot.com/forums/plumbing/sentinel-x400.341370/page-2#2549057

 

[Agile]

That was just one person who said he is using it and not a professional using it regularly.

I don't see much purpose for it as X800 would be the normal cleanser and after properly cleaning with it there will be virtually no dirt left.

Tony

 

[AlexCarp]

X800 needs a flush after use?
X900 does not?

Any offers.

There must be a difference in X800 and X900, why would they make two products?

 

[mattysupra]

Powerflush required.
Not been done properly maybe?
How was it powerflushed before?

Hi, sorry for the delay replying.


Powerflush done twice. They connected a large cylinder to it and left running for a few days. Been done twice by two different firms.

 

[mattysupra]

Could be the plastic pipe.

If the filter is full of sediment, why clean it at three months and not much sooner. The purpose of installing this unit is to catch the muck before it enters the boiler. If it is full at three months, then it has not been very effective as it is full and now the muck is entering the boiler and blocking up the filter. Catch it before the the muck starts moving into your boiler

Stop emptying your system also. Each time you fill your system, fresh water that is put in the system will have air in it that will be react with system components to produce black muck you are trying to get rid of. One thorough cleanse and treatment is all that is needed

Should i have to empty it every 3 months? Every other house i have lived in the boilers have been many years old and run without issue or a filter.

So its normal then for the filter to be full of crap every 3 months and i should clean it out sooner like every month maybe? How come i have not had to clean filters out in the past, the boilers in the past have had no filter?

Also every time i open the filter im getting air in there. So if i was to empty more often then more air?

 

[Agile]

You need to clean the filter as soon as it has much dirt in it.

No wonder your boiler gets clogged if you have all this dirt circulating.

Tony

 

[DP]

Matt, the amount of sediment in the system depends on how the system was installed, materials used and type of maintance work carried out during its lifetime. Some really old systems if installed correctly, will have a reasonable amount sediment with minimal disruption to new boiler. On the other hand a younger boiler with installation issues would be struggling like a person with duff lungs.

The filter is there to intercept the clogging particles before they enter the boiler. Do your filter cleaning much sooner to remove the problematic sediment. As the amount of sediment in the filter gets less the period between cleaning can be extended.

 

[McCombi]

Powerflush required.
Not been done properly maybe?
How was it powerflushed before?

Hi, sorry for the delay replying.


Powerflush done twice. They connected a large cylinder to it and left running for a few days. Been done twice by two different firms.

What you're describing there sounds like a cleanse with magnets has been done. Or was someone actually there with a machine which would be plugged in and pretty noisy as it has a pump fitted, doing each radiator individually, draining out crap refilling etc. job usually takes a day.
If chemical was added and magnets were set up to collect crap and left for couple of days to circulate, that is not a powerflush.

 

[gigz]

I read in old threads that putting in a plate heat exchanger and another pump solves the problem as the boiler water only pumps around the plate heat exchanger and does not come in contact with the water in the radiators.

This might stop your boiler clogging up, but will block the plate heat exchanger. Have you got any crap cheap radiators ? You also have problems if you have too many different materials (iron/copper/stainless/aluminium etc) on your system. After all the cost and polava you're having i would seriously consider getting a water sample tested (think fernox do it but don't know the cost) Worth enquiring about maybe.