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.

Glowworm Ultimate Whining Noise

I was called out at the weekend because a customer was concerned at the noise their boiler was making. Unusually I could even hear it over the phone whilst the customer was talking to me. It was quite a high pitched noise and almost sounded like there was a washing machine on fast spin. As soon as I heard it when I was in front of the boiler I could immediately tell that it was the fan that was making the noise.

Due to the was these boilers work the fans are subjected to quite high temperatures over their lifetime and it is no surprise that they fail. The bearings in the motor often dry out and begin to emit a whining noise. If left too long the friction in the motor can cause the fan to seize and burn out. Fortunately the customer was wise to the fact that something wasn't quite right and called me before they were left with no heating or hot water.

I replaced the fan, each if which is different for each model. The fans come on a plate which has varying sized holes in the bottom depending upon the boiler size. Also the bigger boilers have bigger windings on the fan to increase the rotation speed and exhaust of gases. The boiler is now running much better and the customer was surprised how much quieter the new fan is.

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.

Hot Water Staying Hot Even Though Turned Off

A customer rang me to have a look at his hot water today as he was getting plenty of hot water even though it had not been set to come on for almost a week. Quite often I go to have a look at this fault to find that the immersion heater has been turned on by the wife or kids! When I looked in the airing cupboard the immersion heater was wired into a plug and clearly unplugged.

Looking at the timer the central heating was set to be on through the day and the hot water was off.  I turned up the room thermostat to bring the pump and boiler on. I then waited in the airing cupboard feeling the pipes to find out where the heat was going. The heat appeared between the pump and motorised valve first of all and could be felt going to the radiator circuit. The radiator circuit being port A of the motorised valve. The pipework between the valve and the motorised valve was very short making it difficult to gauge the temperature of the hot water travelling within the pipe due to the transfer of heat back from the cylinder. I felt the pipe on the cylinder return, which is the lower connection and could feel it slowly starting to get warm.

I decided that it was almost definitely the motorised valve at fault and decide to replace it. When the valve had been removed I could see that when the valve was in the central heating position port B for the hot water was not being closed off fully. Had the valve been open wider I'm sure the customer would have been complaining that their hot water was excessively hot because it would have been heating the whole time the heating came on.

I replaced the motorised valve and retested the system to make sure that the valve was moving as it should and that their was no air in the system and all the radiators got hot. Once everything was up and running I left the heating and hot water set on the timer.

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.

Boilermate 2000 No Hot Water

I was called by one of our customers because she had no hot water, and running a hair styling business from home it was urgent. I visited to find a Glowworm Ultimate and Boilermate 2000 cylinder. The lady had tried to put the electrical boost function on the cylinder but was still not getting any hot water.

I looked inside the cover of the Boilermate 2000 cylinder and could see that the display on the PCB was blank, although two of the green LEDs were lit and two of the pumps were running. Pushing the little buttons on the PCB to toggle through the displays of the circuit board was not having any effect. For some reason the PCB had failed and was no demanding heat from the boiler or operating the boiler pump. There was no GT155 PCB in stock locally or available next day from our suppliers and had to be ordered for the following week.

I looked into the electrical side of the Boilermate Cylinder and could see that the immersion heater had been wired up, and that there was wiring to the cylinder for the electrical side. However, the fuses were pulled out and secured out with a cable tie and the electrical side had never been commisioned at installation. I advised the customer to contact and electrician to check the electrics which got the hot water heating again temporarily until I was able to return with a new PCB.

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.