Knowledgeable Central heating advice appreciated.

badlywornroy

badlywornroy

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Viessmann system boiler, (not combi ) 5 years old, serviced in october. Microbore pipework ( Yuk ) but all throughly cleaned 5 years ago when boiler fitted. Magnaclense inline filter fitted.

Boiler fires up on demand, then shuts down when boiler water temp reaches around 60. Thinks ? . . . boiler safety device. water not being pumped around system.

Boiler does not show fault code.

Thinks ? Pump problem, Grundfos UPS3, shows no error code and is only 3 or 4 years old.

I have today replaced the pump with another Grundfos UPS3.

Exactly the same problem.

I'm banjaxed, any thoughts or suggestions.

Rest assured I will not mess with the 'Gas ' side of the system.
 
Can you get into a 'engineers menu' on that boiler?

We had/have a situation where the heat exchanger fills up with sludge and then boiler short cycles, so the rads get warm but not hot. Boiler claims all is well on the consumer info but getting into the engineers menu lo and behold a code appears - something along the lines of 'early shutdown due to over temperature'. We've got filters and inhibitor in our system but it still builds up sludge within 12 months and needs the manufacturers engineer (Mr Bosch) out to take the boiler apart and flush it. Response is 'oh some still do that for some reason'.
 
What temperature controls do you have on the system? Check the room stat first of all. If the boiler was registered within 30 days it would be under warranty for 7 years. Have you contacted your service guy?
 
BethAtTheHug said:
Can you get into a 'engineers menu' on that boiler?

We had/have a situation where the heat exchanger fills up with sludge and then boiler short cycles, so the rads get warm but not hot. Boiler claims all is well on the consumer info but getting into the engineers menu lo and behold a code appears - something along the lines of 'early shutdown due to over temperature'. We've got filters and inhibitor in our system but it still builds up sludge within 12 months and needs the manufacturers engineer (Mr Bosch) out to take the boiler apart and flush it. Response is 'oh some still do that for some reason'.
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Thanks Beth,

No, I cannot get into the engineers menu. I doubt that it is sludge buildup, the pump I took out showed no signs of a ' dirty ' system and the in-line MagnaClense and inhibitor in the system should keep it clean enough ? Thank you for your thoughts.
 
gerry s said:
What temperature controls do you have on the system? Check the room stat first of all. If the boiler was registered within 30 days it would be under warranty for 7 years. Have you contacted your service guy?
Click to expand...
I have a Hive controller gerry that I installed myself 3 or 4 years ago. I know my way ' around ' it and I'm pretty sure that is working as it should. Unfortunately my ' go to ' heating engineer has left the business ? which I only discovered when I tried to book a visit. Try to get a response from a gas registered engineer, I tried 4 yesterday, not one call back so far.
My boiler had a 5 year warranty which expired in october last year. Meanwhile my wife and I ( 78 and 75 ) are trying to keep warm with a couple of electric heaters. Thankfully, the temperatures are a ' balmy ' 6 degrees here, it was freezing not long ago. Thank you for your thoughts Gerry.
 
seaodyssey said:
Are the motorised valves working, They go wrong often (It maybe a 3 way)
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Yes Pete, the valves are good, they switch between heat & hot water as demanded before the boiler shuts down. Thanks for your input Pete.
 
The pump in our unvented system is quite "high" in the water circuit, so if the system contains insufficient water, the pump has no water to pump, the boiler then overheats and shuts down. So check that there's enough water in the system.
 
does your boiler kick back in and carry on heating just to no more than 60degs?

if so thats what the flow temp might have got set to , we keep ours at about 70 can you find out how to turn up the flow rate and does it respond?
 
The fact that there is no fault code points to it being temperature or flow problem. Could you disconnect the hive and run it purely off boiler temp control to see if that is a fault. I'm certain the viesmann default is 60 degrees so try turning the boiler temperature control up. If all else fails you could ring viesmann customer services on 01952 675000. Open from 8:30, they are apparently very helpful. Good luck.
 
gerry s said:
The fact that there is no fault code points to it being temperature or flow problem. Could you disconnect the hive and run it purely off boiler temp control to see if that is a fault. I'm certain the viesmann default is 60 degrees so try turning the boiler temperature control up. If all else fails you could ring viesmann customer services on 01952 675000. Open from 8:30, they are apparently very helpful. Good luck.
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HI Gerry, yes I was thinking along the similar lines. I have rang Viesmann and booked and engineer but no contact back from an engineer to say ' how long ' So on a recommendation I have a local heating engineer calling tomorrow P.M. Depending what he says, I will either cancel the Viessmann engineer or get him to call. I normally run the boiler temp control on the recommended 4 (marked 1 - 6 ) I will try altering this and see if it has any effect. Thanks for your input Gerry.
 
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With the boiler running to heat the central heating ciircuit, can you hear "kettlling" from inside, i.e the sound a kettle makes as it heats toward boiling? If you can that indicates the water isn't circulating fast enoughand is boiling within the primary heat exchanger, which will cause the boiler to cut due to flow and return temperatures being too far apart.

The cause of this is build up of crud (limescale) on the small pipes inside the primary heat exchanger with restrict flow so the slowly moving water boils rather than simply gets warmed up to the desired flow temperature.

Solution either a new primary heat exchanger ££££££ or put a bottle of x800 into the systemand run it rounda single radiator (turn all the others off) with the flow temp set very low to try to stop it cutting. Do that for a few days and see if it improves, then drain the whole system and refill.

I learned all this the hard way, having already replaced the diverter valve and secondary heat exchanger when my boiler gave up. Utlitmately a £15 bottle of cleaner fixed it after I'd spent hundreds.
 
Thank you for your reply Mark,

A gas registered engineer called yesterday. The boiler was on and working. Sod's law ? I had tried the CH early in the morning and it ran perfectly ? this has been an intermittant fault for approx 2 weeks. The engineer immediately adjusted the pump speed 'down ' he said it was set to high for my size of house ( smallish 3 bed detached) and microbore ( Yuk) piping. He explained how this could possible be causing flow problems that would cause my Viessmann boiler to shut down ? (Viessmann being great boilers but ' sensitive ' to certain conditions.) When I fitted the pump I left it at default settings. (well why not )
Anyway, he was a lovely bloke and had all the time in the world for me and said he would return asap if the problem returned. He is local and will now be my 'GoTo' engineer. My previous engineer has recently left the trade.
Let's hope that is an end to this ?
 
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An update to possibly help anyone who stumbles over this thread.

This problem returned once or twice over the following 6 months i.e boiler 'short cycling ' and shutting down. Only to then run normally for a while. As luck would have it in october when my boiler was being serviced the fault repeated itself. To cut a long story short the engr diagnosed the fault as a pipework blockage due to a dirty system. The system was drained down, some pipework was removed and a blockage was found. System refilled, new MagnaClean fitted and system has been running fine since.
N:B I would never knowingly again buy a house with microbore pipework. It is a quick(er) cheaper way to install CH. Common sense tells me 8mm or 10mm pipework is sure to be less efficient and more prone to blockages than standard 15mm pipework. You have been warned. :confused:
 
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