Flush system to stop potterton profile 100e overheat sensor

[AdeO]

Hello, sorry this is my first post, but from the articles I’ve read you all seem to be a helpful bunch.
I’ve got an old open vented pumped system. It was completely overhauled in 2006, over the last couple of weeks the potterton profile 100e has been tripping the over heat sensor, and having to reset 2-3 times a week. I’ve been cleaning the magna clean and it is collecting sludge and coarse fragments at least once a week since the problem started. I did drain down the F&E about 2 weeks ago and put a bottle of fernox mb1 in, but still a problem.
Before I call the big boys in to do a power flush, I’m thinking of the following.
Drain down system (initial flush).
Add Sentinel X800, run CH @ 30oC for 4 hours, drain down again. Then refill with another fernox mb1 & f1 (boiler silencer) or just add a Sentinel x400 and flush again in 8 weeks. The house is a 4 bed, with 6 upstairs, and 7 downstairs radiators.
Do I need more than 1 bottle each time, and is this logic sound, or am I wasting my time?
Many thanks to all who contribute positively to this post.

 

[bazdaman]

One bottle of any central heating chemical typically does 10 rads which is estimated about 100 litres so i would use 2 bottles of inhibitor, x800 is quite strong so i would start by adding one bottle and running for a day and draining out refilling and test to see if that has helped before adding inhibitor as you might have to bang some more cleaner in and you dont want to waste 2 doses of inhibitor. If system is very dirty on draining think about removing rads and flushing through with a hose if you feel you can.

 

[Agile]

Before I did any water treatment I would be doing a thermal survey on the boiler so that I could understand what is going wrong.

Only then would I feel capable of providing a solution!

Tony

 

[AdeO]

many thanks bazdaman & Tony,
I've drained down system added x800, kept in system for around 8-10 hours, the wife and kids said it was too hot when I initially ran it for a couple of hours (target temp was 30, but was unbearable at 26.5) so turned heating off.
Drained down system this morning, re-filled, ran heating with boiler off to circulate the clean water round. flushed again and left f&e open, so water was flowing for about an hour through system, then out via lowest rad and hose to outside drain.
added 2 x sen x100 + sen x400, will flush again round dec.
think Tony is right, it might be boiler orientated as when I ran it hot yesterday, I noticed that when it reach target temp (heating and water) both motorised values shut off, and the water was circulating in the loop. shortly after this I had to push the thermal trip button up again, so might be thermal sensor on boiler?
thanks to all.
cheers Adrian

 

[Agile]

added 2 x sen x100 + sen x400, will flush again round dec.

cheers Adrian

You should not have added X100 and X400 together!

Whilst it will do no harm, only one X100 is needed.

After using X800, if done properly and then X100 added it will not need cleaning again for many years!

Tony

 

[AdeO]

Many thanks Tony, the system hasn't be serviced since it was overhauled back in 2009 (got heating company to change from gravity to fully pumped, change a few rads, add a room stat, tlv's, magna clean, inline inhibitor, etc)
think it was overdue a good clean

thinking about replacing the overheat sensor and then boiler pcb if problem continues.

read on another article inlet and outlet temp should be +/- 10C difference, not sure how best to test this or if there is a heating thermometer to do this with I could buy.
many thanks.

 

[45yearsagasman]

If you have a multimeter, or can borrow one, then temp sensors are readily available. You will then be able to measure the flow differential. I would also add that a 100e for 13 rads may be a tad oversized. How good and clean is your pump? Lots of things to check. A pcb would not be causing your problem.

 

[AdeO]

many thanks Pete, think its a 100e, that seems to be what is mentioned on the lower plastic tray of the boiler when I ripped it off last week.
the pump was replaced same time as the overhaul, it's a Grundfos 15-50. it seems to be whizzing round fine (can hear difference in spin when using the speed selection switch), and can hear it pumping the water (as well as the air initially after the refill), there is a Honeywell automatic air vent value as well, so all air is now gone.
I have a multimeter, so I actually take the reading from the boiler PCB rather than an alcohol thermometer on the pipes ingress/egress the hw tank/ch circuit?
thanks again.

 

[AdeO]

sorry just saw this when trying to find out what the air vent was called, also have one of these on the loop to boiler (i.e. where the water loops when the ch & hw motorised values have shut down);
http://www.plumbase.com/tprod75121/section1821/hwell-ang-auto-bypass-valve-22mm-du145.html
honeywell du145 automatic bypass valve 22mm

 

[Agile]

If you have a multimeter, or can borrow one, then temp sensors are readily available. You will then be able to measure the flow differential.

Where do you expect him to find temp sensors in his boiler?

Boiler temps need a contact thermometer for measurements.

An IR thermometer is not much good

Tony

 

[AdeO]

no worries, will get two thermometers, something like;
http://www.heatingcontrolsonline.co...r-p-644.html?gclid=CJudt-63iboCFbIPtAod734ANw
should do the trick, presume this needs to be in airing cupboard rather than above boiler, two crude photos attached (sorry bulb in inspection light popped the other day, so airing cupboard is dark, the pump is at the back of the photo below air vent spur.
thanks Adrian. View media item 67431 View media item 67432

 

[Agile]

They are not massively accurate but probably good enough.

But FIRST compare the temps shown when both are on the same pipe.

They can take about 10 min to stabilise too.

Best on the boiler flow and return pipes close to the boiler!

But their response time is too slow for professional use.

Tony

 

[AdeO]

many thanks Tony, will buy a couple to verify, might be a bit difficult placing close to the boiler, as not much clearance at the top, plus would need a ladder to take the measurements
cheers Adrian

 

[Agile]

The cost of two will be little different to a cheap ( Maplin sale ? ) meter with a wire ended thermocouple sensor.

They respond within 10 seconds when pressed onto a copper pipe or fitting.

Tony

 

[45yearsagasman]

Where do you expect him to find temp sensors in his boiler?

Mr Glazier, I expect him to buy some to use with a multimeter.