Main Combi HE Dripping Water

I received a call from a customer because they had water dripping slowly from the underneath of their Main Combi HE. Knowing these boilers quite well I had a goood idea of what the issue might be before I got there. When I got there I could see that the water was dripping from the left-hand side close to the front. I removed the front casing and dropped the controls casing down to reveal the inside of the boiler. Instantly I could see that the water was leaking from the differential pressure switch on the front of the diverter valve which is a common problem.

The diverter valves and differential pressure switches can also be found on other boilers (Baxi Combi 80, Baxi Combi 105, Potterton Performa and Alpha 240/280) and it is not uncommon for them to leak. The leak usually comes from where the pin exits the hex nut behind the micro-switch and worsens when the hot tap is run. I had an Interpart diapragm kit and so dis-assembled the differential pressure switch. Whenever I strip one of these down I always clean the pin with a bit of wire wool as there always appears to be some scale build up on the pin which could damage the seal on the new hex nut.

I reassembled the boiler and turned the water back on and tested that the pin was moving as it should be without leaking and that the boiler was behaving as it should be.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

One Cold Radiator In Extension

I was asked to a look at a radiator recently that had not been working since the heating had been turned back on. The radiator was upstairs in the master bedroom which had been extended a few years previously and the radiator relocated. All the other radiators were nice and hot, and there was 16 other radiators. The customer had tried bleeding the radiator and to remove the head of the thermostatic radiator valve, but neither of these attempts got the radiator working successfully.

I removed the remainders of the head from the thermostatic radiator valve and pushed on the pin which was moving up and down perfectly. I then checked that the lockshield valve was fully open at the opposite end which it was. If there was an issue with balancing or circulation I would have expected one of the bigger radiators below to have been affected rather than an upstairs bedroom radiator.

I ensured the room thermostat was turned up fully and went around the house turning off all the other radiators. I checked back at the problem radiator and it was getting hotter to the pipe but the water was still not circulating through it. I looked in the airing cupboard and the system had two zone valves fitted and a bypass. The hot water was satisfied and the zone valve was closed accordingly, and I closed the bypass off. As soon as I turned off the bypass the full force of the pump pushed some air out of the pipework to the radiator and I heard it gurgle. Almost instantly the radiator was hot all over, and so I went around and turned all the other radiators and bypass back on.

The radiator continued to heat with the rest of the system up and running. I expect that over the summer air settles in the pipework to the radiator and prevents the circulation around that radiator. I expect when the radiator was relocated the installer used plastic pipe which because of the way it is often coiled never lies completely flat and leaves high points in the pipework for air to collect in.

Potterton Flamingo No Heating Downstairs

I received a call from a customer today that was worried about her heating. The radiators upstairs appeared to be working fine, but there was no heat at any of the radiators downstairs. It didn't matter that she turned the room thermostat right up they were not getting hot and when the boiler did come on it was only for a short period.

The programmer was set to constant for both heating and hot water, and the room thermostat was turned up high enough that the central heating should be on. Checking up in the airing cupboard the hot water was up to temperature and the motorised valve had moved over fully to the central heating position. The pump was also running although it didn't quite sound right. I thought that the cold feed may have been blocked but I felt the feed and vent and they both felt hot quite a way above where they tee in.

Pausing the rotation of the pump by moving the speed selector switch to a position between speeds didn't cause any gurgling which would suggest air or a lack of water preventing circulation. I also checked that the pump valves were both fully open. As everything seemed to be as it should I assumed that the pump was not spinning at the required velocity even though it did not look that old. I replaced the pump and switched the system back on and soon enough the radiators downstairs began to get warm.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

Glowworm Flexicom CX Heating Not Working Properly

A friend of mine who is also a heating engineer asked me to look at a Glowworm Flexicom CX which a customer of his was having trouble with. He had serviced the boiler 6-7 months ago and the lady had called him back because it was not working correctly and hadn't been since he had serviced it apparently. During the summer one of the radiators had been getting hot when the hot water was run for extended periods and warm even when the hot water was run for shorter periods.

With the winter weather turning colder the lady began to use her heating and not all of the radiators were getting hot. Two of the three upstairs radiators were getting red hot, the other lukewarm. One of the radiators downstairs was getting lukewarm but the others were hardly getting warm. The boiler was getting up to temperature really quickly and then cutting off taking a while to cool down before relighting. When the status display was on it would run through the central heating status mode as normal eventually ending up on S7 the central heating pump over-run status. Then it would go to S97 where the boiler checks the water pressure sensor, and suggests you check the connection to the water pressure sensor and that the pump has not seized. Both of which appeared to be fine. The boiler flow was very hot when the boiler was running and the return was barely warm.

Another engineer had previously removed and cleaned out the water pressure sensor just after the boiler had been serviced and said there was a fair amount of debris fouling it. My friend also said that there was some debris when he drained one of the radiators. From this I assumed that the diverter valve may have been fouled with debris and not moving correctly between the heating and hot water positions. I drained the boiler and removed the diverter valve. To remove the diverter valve all three of the screws had to be removed fully before the diverter valve would come out, the bottom one was particularly tricky to access but managed to get it out with some needle nosed pliers.

After removing the diverter valve the remaining water in the boiler which leaked inside the boiler was really clean and there was no sign of any debris in the diverter valve. However it didn't look as if the motor was attached to the spindle of the diverter valve. I removed the motor from the diverter valve assembly and the spindle was free to move. I reconnected the spindle and fitted the motor back to the diverter valve assembly.
I then re-filled and tested the boiler. I ran the hot water and it was heating and modulating as it should to heat the water to an even temperature. I then switched the heating on and the motor moved the diverter valve in towards the back of the boiler and the connection to the spindle was visible through the hole in the diverter assembley close to the white plastic section. Opening the tap the motor pulled the spindle back outwards, and stayed there for a while after the tap has closed before the motor pushed the spindle back in.

I checked around all the radiators and they were all getting hot as they should be.

Potterton Promax Combi HE Low And High Pressure, Poor Hot Water

I was asked to service a Potterton Promax Combi HE as it had not been serviced since it had been installed. It was not that old but should have been serviced annually. When I arrived the customer had a list of issues with the boiler which also required investigation.

• The boiler keeps losing pressure
• The water pressure in the system keeps going into the red
• The hot water keeps going hot and cold
• One or two of the radiators were getting hot even though the heating was off

I looked over the boiler and asked if they had noticed any water leaks, which they hadn't. I looked at where the Pressure Relief Valve is terminated outside and could see that there was signs of it having let water out of the system. Having been leaking for while the PRV would require replacing as it was fouled with scale and debris from the system.

I topped up the water pressure to 1 1/2 bar and turned on the central heating system. It was not long before the water pressure in the system had risen and was close to the red. I turned off the heating and drained the pressure out of the heating system and checked the pressure in the pressure vessel. The pressure was low and with the drain point still open I increased the pressure in the vessel to the recommended amount through the schrader valve.

After setting the boiler back up I ran the hot tap and after running off the cold water in the leg of pipework it began to come through reasonably hot, and then cold, and then hot again and kept cycling like this without getting up to a satisfactory temperature. Watching the boiler I could see that it was rapidly getting up to temperature before cutting out, and was not transferring this heat to the hot water. When the boiler got up to it's maximum temperature it would send hot water out to the radiators explaining why a couple of the radiators had been hot at times through the summer. I removed the hot water plate heat exchanger and could see that it was quite badly blocked with debris and sludge from the system.

I replaced the PRV, plate heat exchanger and fitted a Adey Magnaclean filter to the system to protect the boiler from getting blocked again in the future. The system was only three years old and had been completely repiped with new radiators and treated with chemicals and yet surprisingly was in quite a bad state. I believe that some of the old pipework must have been re-used under the floor which was already fouled with scale and debris and not cleaned sufficiently when the new system was installed. Hopefully the Magnaclean will pick up the worst of the debris and keep it working as it should be.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

Vaillant Turbomax Boiler Leaking

A customer of ours had a Vallaint Turbomax in a house that they recently moved into, which they had asked us to replace because of its age and inefficiency. They also wished for us to relocate the boiler to another area. The Vaillant Turbomax was of the VU/VUW range with the green control knobs. A week before we were going to replace it, a leak appeared from the underneath of the boiler.

The leak was only slow but needed immediate attention as the pressure was being lost from the system in less than a day. I could see that the water was coming from the right hand side of the boiler but could not see exactly as there was a panel on the underneath of the boiler. I opened the lower panel and dropped the controls down to see the diverter valve, etc. It was immediately obvious that the leak was coming from the automatic air vent, as there was water steadily appearing from the bleed pip.

I tried to screw the bleed pip down to stop the water from coming out of the cap but it would not seal. I dropped the pressure from the boiler and removed the top of the AAV. The float and mechanism of the AAV was fairly dirty and I may have been able to clean it up. However, I had a new AAV in the van which I dismantled and fitted to the boiler. This repair kept the boiler leak-free for another week and I was able to retrieve the AAV innards after replacing the boiler.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.

Glowworm Ultimate No Heating or Hot Water

After returning from a holiday abroad to the cold of this country one of my customers had to call me out because they had no heating or hot water. The first thing I did was look at their Glowworm Ultimate boiler because they said that they could not see the pilot light. I removed the bottom tray and could see from the gas valve that there was no permanent pilot and that being the fan-flued Glowworm Ultimate had automatic ignition (the pilot lights itself as and when the boiler needs to fire up).

It was at this point that I noticed that the overheat button on the controls fascia was sitting out. I pushed on the button and sure enough it clicked as I reset it. As soon as I reset the overheat button the boiler came to life and fired up. I hung around at the boiler for a moment to ensure that the system was circulating and not likely to overheat immediately. The boiler was running fairly quietly so went to check around the rest of the system.

I told the customer that it may have been caused by a bit of air or if there was a power cut whilst the boiler was running. He replied by saying that he had been having unrelated issues just before he went on holiday. He had asked a friend of the family to replace the immersion heater which turned out to be faulty and kept tripping the electrics until it was replaced with another unit. The plumber had also broken a part on the heating system and ended up draining and refilling the system to replace it and the pump. Like I had already said the boiler overheating was either due to cutting out of the electrics or air in the system. After resetting the boiler the system is working as it should be again.

Disclaimer: The works described in this blog are a record of work undertaken and should not be taken as guaranteed to solve your problem. Work should only be carried out by persons qualified and competent to do so.