Hello All
Please bear with me as I am new to the forum and have turned to the forum for help.
I have a Potterton Suprima boiler with a Ariston contract STI 210 water cylinder. My central heating and hot water stopped working last week. I called a plumber who my dad has been using for years. The boiler was locking out and he diagnosed the fault being the pump. He got a new pump and changed it and the problem remained. He then said that the problem must be the PCB. Now I did some research on the net and on this forum and realised how problematic these PCB's were. I thought that must be it and I got a replacement PCB and replaced it, the problem was still there. I discovered that the PCB in my boiler had at some stage been upgraded to the new PCB anyway. The plumber thought it must be the PCB and made me change it for a second one to find the problem hadn't gone away. He then carried out further test and advised to change the thermistor and heat stat. He changed the thermistor and then wired the new heat stat but did not take the old one out of the pipe but confirmed to me that it wasn't the heat stat. So now the boiler would fire run for 5 seconds then shut down, it would do this 3 to 4 times and then lockout with the redlight. He had given up and then as he was packing up he noticed that if he only turned the hot water on from the timer switch that the boiler would run and continue to run. He then turned to the the mid position valve by the tank and proceeded to remove it. He manually turned the valve to the central heating position and left it running. The boiler seemed to work in this way for a day or so. It then once again locked out. He changed the actuator for the divertor valve thinking this would resolve the problem but it didn't. SO he removed the new actuator and the wiring for it and left it off. He then put his hands up and said that he could not fix it and that he had been beaten.
So I then looked for another plumber and a friend recommended his brother in law. I had him around and the first thing he wanted to do was put the actuator back. He wired the actuator back which took him a while as the wiring was removed by the previous plumber and he had to work out where the wires went back to. He then diagnosed that it might be the actual mid position valve and so drained down the system and changed the valve. After refilling the system he wasn't having any joy and proceeded to mess around with the wiring as he wasn't sure that it was all wired correctly and continued to moan about the wiring not being easy as it wasn't colour coded. Anyhow in the end he couldn't get it going the way it should.
So I was in the end back to square one. If you put the hot water on the timer switch alone the boiler would fire up and both heating and hot water would heat up. However, if you turned the heating on from the timer switch then the boiler would lockout.
What I noticed was everything was getting very hot when running like this(only hot water on at timer switch) the boiler case was getting very hot the pump was getting very hot.
The boiler would run like this get to temperature and then stop and then run again then stop.
The last plumber said as he left that it must be the room stat as nothing was happening when this being turned on and off or its the timer switch which is a Danfoss FP715. And that I might need an electrician.
Does anyone on here have any ideas to what this problem may be?
Please bear with me as I am new to the forum and have turned to the forum for help.
I have a Potterton Suprima boiler with a Ariston contract STI 210 water cylinder. My central heating and hot water stopped working last week. I called a plumber who my dad has been using for years. The boiler was locking out and he diagnosed the fault being the pump. He got a new pump and changed it and the problem remained. He then said that the problem must be the PCB. Now I did some research on the net and on this forum and realised how problematic these PCB's were. I thought that must be it and I got a replacement PCB and replaced it, the problem was still there. I discovered that the PCB in my boiler had at some stage been upgraded to the new PCB anyway. The plumber thought it must be the PCB and made me change it for a second one to find the problem hadn't gone away. He then carried out further test and advised to change the thermistor and heat stat. He changed the thermistor and then wired the new heat stat but did not take the old one out of the pipe but confirmed to me that it wasn't the heat stat. So now the boiler would fire run for 5 seconds then shut down, it would do this 3 to 4 times and then lockout with the redlight. He had given up and then as he was packing up he noticed that if he only turned the hot water on from the timer switch that the boiler would run and continue to run. He then turned to the the mid position valve by the tank and proceeded to remove it. He manually turned the valve to the central heating position and left it running. The boiler seemed to work in this way for a day or so. It then once again locked out. He changed the actuator for the divertor valve thinking this would resolve the problem but it didn't. SO he removed the new actuator and the wiring for it and left it off. He then put his hands up and said that he could not fix it and that he had been beaten.
So I then looked for another plumber and a friend recommended his brother in law. I had him around and the first thing he wanted to do was put the actuator back. He wired the actuator back which took him a while as the wiring was removed by the previous plumber and he had to work out where the wires went back to. He then diagnosed that it might be the actual mid position valve and so drained down the system and changed the valve. After refilling the system he wasn't having any joy and proceeded to mess around with the wiring as he wasn't sure that it was all wired correctly and continued to moan about the wiring not being easy as it wasn't colour coded. Anyhow in the end he couldn't get it going the way it should.
So I was in the end back to square one. If you put the hot water on the timer switch alone the boiler would fire up and both heating and hot water would heat up. However, if you turned the heating on from the timer switch then the boiler would lockout.
What I noticed was everything was getting very hot when running like this(only hot water on at timer switch) the boiler case was getting very hot the pump was getting very hot.
The boiler would run like this get to temperature and then stop and then run again then stop.
The last plumber said as he left that it must be the room stat as nothing was happening when this being turned on and off or its the timer switch which is a Danfoss FP715. And that I might need an electrician.
Does anyone on here have any ideas to what this problem may be?
