Friday, 14 December 2012

Hot Water Not Getting Hot, Heating Getting Too Hot

I was asked to look at a heating system because the lady was not getting any hot water when the boiler was on, and the only way she could get the hot water to heat was to put the immersion heater on. Also, she had also been struggling to control the temperature of her radiators. Even with the room thermostat turned down low the radiators were still heating up.

Looking in her airing cupboard there was a Honeywell V4073 three-port valve. The hot water was set to be on and the room thermostat was turned down low. Feeling the flow and return to the cylinder both pipes were only slightly warm. Feeling the lever on the valve head it was loose, and moved easily from side to side with no resistance. This indicates that the valve was open for the heating. 

After removing the casing from the valve I attempted to move the mechanism back to the hot water position manually. I was unable to do so and so removed the head from the valve body. As soon as I removed the valve head it sprung back to the hot water position. I felt the spindle on the valve body and that appeared to be moving with little resistance.

I replaced the motorised valve head with a new one and tested it's operation. The valve was operating correctly and heating was restored to the hot water cylinder.

Potterton Suprima Red Flashing Reset Light

Was called by a gentleman today who I had done work for in his previous house. He had moved to a new property but had been having trouble with the boiler and thought it needed servicing. I visited to service the boiler and look into any issues he was having with the boiler.

The boiler was a Potterton Suprima and the gentleman was regularly having to press the reset button as the red light was often flashing and the boiler was not running. The fault had been happening for the past six months but was gradually worsening. There didn't appear to be any set pattern as to when the boiler would lock-out and the red light would start flashing.

Pressing the reset button would get the boiler going again and it would carry on working for a few days without issue. However, being the winter, the problem was getting more of an issue as the gentleman would get up to find he had no heating or hot water just when he needed it.

I looked over the boiler and serviced it at the same time. The electrode looked to be clean and have the correct spark gap. The ceramic on the electrode looked to be in good condition. The ignition lead was not the original and it may have been that both the electrode and lead had been replaced in the past. The old electrode lead were prone to breaking down and causing ignition problems, they are sheathed with red insulation. The new electrode leads are sleeved in clear plastic, and thicker black plastc where the lead passes through the case.

It is a possibility that the boiler was overheating due to a fault with the thermistor and/or overheat thermostat but in my experience these generally fail and the boiler will lockout every time it runs. I have also experienced the gas valve failing to open which prevents the boiler from lighting. Again, I have found that this usually fails and cannot be resolved through pressing the reset button.

I dropped the panel down to reveal the PCB and could see that there was some signs of scorching to the PCB near the centre of the board. This is common on these PCBs and I expect is related to the lockout issue. There is usually a manufacturer's sticker on the PCB either on a relay or a semiconductor chip which has a sate code on it. This particular PCB was made in 1998 and has lasted well. There is also a date code in the bottom right-hand corner of the data plate, which again was 98, indicating that it was the original PCB.

I replaced the PCB with the new upgraded PCB kit, 5111603. This comes with a new PCB, housing, wiring loom and ignition leads. After fitting this part the boiler has been working well with no issue for the past fortnight.

Tuesday, 11 December 2012

Heating and Hot Water Won't Turn Off

I received a phone call from a concerned customer because her boiler was running continuously and her hot water seemed to be exceedingly hot even though both the heating and hot water were turned off on the programmer.

A colleague of mine was in the local area and so he went round to check it out. Sure enough the boiler was still running when he arrived and the house was like a sauna. My colleague removed the programmer from it's baseplate and the boiler went off. Assuming that the problem was with the programmer he replaced it, tested the operation of the three-port valve and left as everything was working fine.

A couple of days later and I receive a phone call from the same lady because her heating and hot water won't turn off again. I went round straight away to find the boiler constantly running and the house like a sauna. The lady had turned the room thermostat right down and both the heating and the hot water off on the programmer.

I looked at the electrics and checked what voltage were where. There was 230 volts at the grey, 24 volts at the orange and on the white wire of the Drayton MA1 three-port valve the voltage exceeded the scale of my Fluke T3 Electrical Tester. It would seem that 24 volts is enough to power the switch live of the Worcester 15 Ri boiler which was fitted.

I disconnected the orange wire and hot water calling from the switch live to the boiler and the boiler went off.  The voltage was coming from the orange wire of the three port valve. I replaced the head on the motorised valve and re-tested the operation of the heating system, which has been working correctly for the past week.

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.

Wednesday, 28 November 2012

Worcester Bosch 28CDi No Hot Water

I was asked by a lady to look at her Worcester Bosch 28CDi combination boiler because her hot water performance had been gradually declining before failing altogether. The decline occurred over a couple of months and first began to affect the upstairs taps. The lady had already called another engineer who gave her a price to replace the entire diverter valve, and asked me to give her a price as we had previously done work for her.

When I arrived the lady explained everything to me and so I tested the boiler to see what was happening. I ran the hot tap and nothing happened at the boiler. From below the boiler you can see the operation of the diverter valve and differential pressure valve. As I ran the hot tap the pin was hardly moving if at all to operate the hot water micro-switch. The lady explained that the hot water did work to some extent if the central heating was on. I put the central heating on and again opened a hot tap. Still the pin was not moving to an obvious degree. I asked about the temperature of the hot water as it was barely warm and the lady told me that it only came through hot once the heating had been on for some time.

It may have been that the boiler could have been repaired by replacing just the diaphragm inside the differential pressure valve. As the hot water had not been working at all and there was no visible movement of the hot water pin I decided that it would be best to replace the whole diverter valve as this is what I had quoted to do. I had brought the relevant diverter valve with me which are relatively inexpensive and fit a number of different boilers. Fortunately the valve also came with the associated o-rings and washers to make the job run smoothly.

I turned off the water supply and drained the water system as far as possible. I turned off both the valves to the boiler on the central heating circuit after warning the lady that they may require replacement. Operating the valves on a combination boiler is something I try to avoid doing as they often begin to leak due to their in-operation over the years. I chose isolate the boiler at the flow and return valves because the boiler was on the ground floor and only 18 inches off the floor which means it was one of the lowest points of the system. I then opened the white plastic drain points on the boiler which were completely blocked. Fortunately the boiler was high enough off the floor allowing me to get a bucket underneath and use a thin screwdriver to unblock the drain points.

With the boiler drained as far as possible the first task was to remove the filling loop. There are two screws at the left hand end that secure it to the heating manifold and it just pushes in to the water differential valve and seals using an o-ring. There is a metal plate which prevents the filling loop from moving to the left and coming out from its position. Once the two screws on the left hand end of the filling loop are undone the plate can be swung down and the filling loop gently twisted to get some movement before disengaging it from its location.

The next job is to remove the plate heat exchanger, which usually contains some water still and is worth putting a towel over the pcb housing for some extra protection. There is a clip on the top right of the plate heat exchanger which is held on by a screw which need to be removed. There is also a nut which needs to be undone and secures the plate heat exchanger to the diverter valve. The other two connections are just push-fit connections sealed by o-rings. So once the nut and the clip are undone the plate heat exchanger should be eased off the other two connection with a gentle twisting motion trying not to drop too much water over the pcb housing.

Now the diverter valve should be accessible.

The diverter valve needs to be removed in one piece with the differential pressure valve. Firstly, I disconnected the copper bypass pipe connected to the plastic flow manifold. I then undone the heat exchanger connection nut to the top of the diverter valve assembly. I pulled off the circlip securing the micro-switch to the right-hand end and pushed it up out of the way. There are a number of screws to be undone, I removed all the screws for the bracket on the right-hand end and four on the plastic flow manifold. The diverter valve should now be free to come out of the boiler. This diverter valve took some persuading as it was the original, I managed to add some leverage using a large screwdriver between the rear of the boiler and the diverter valve assembly.

Re-assembly is relatively straight forward if you replace and grease all the o-ring. The most stubborn o-ring to remove was the o-ring between the plastic flow manifold and the flow isolating valve. Due to its location it was difficult to get at and remove. I managed to get a thin screwdriver underneath it and snip it with the point of my Stanley knife. Fitting the bypass pipe back into the flow manifold before securing the flow manifold is also advisable. Don't forget to fit the new filter mesh to the cold water inlet. The metal locating bracket for the filling loop also needs to be slid over the diverter valve connection before refitting the plate heat exchanger. The plate heat exchanger wasn't lined up correctly the first time I fitted it and would advise to connect the nut to the diverter valve first.

Once everything was back together, I refilled the water and heating system. Fortunately there was no leaks. I tested the operation of the hot water which was working perfectly. I then tested the heating system and checked the radiators for air. Overall the job took 2 1/2 hours and I had only allowed 2. With the experience from this job I may be able to get it down to two hours but may quote for three in the future and take my time.

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.

What can a new Boiler give you? by Tom Key, Direct Heating Supplies

This is a guest post from Tom Key, the Online Marketing Coordinator at Direct Heating Supplies. Direct Heating Supplies are one of the UK's leading suppliers of plumbing and heating supplies.

What can a new Boiler give you?

What do you look for in a boiler? Reliability? Cost effectiveness? Durability? The good news is that a new boiler can give you all of these things and more.

An inefficient, old boiler can cause much frustration and can also cost you a lot of money to restore it to full working order.

It is highly recommended that you arrange for gas and oil boilers to be serviced on a regular basis to clarify that your boiler and corresponding heating system is working efficiently in the appropriate manner.

Having a heating engineer out to look at an older system every year can help you to ensure that your boiler is working to the highest levels of heating efficiency possible (which can contribute towards a significant financial saving) and can help you to identify and resolve any potential issues before they get out of hand.

Unfortunately there are some times when you have to face the inevitable and acknowledge that to get the best levels of heating performance you may have to move to a new boiler that can offer a massive improvement in performance.

Older boilers generally offer a less efficient performance, purely due to the improvements in technology within the heating industry.  For example, the condensing technology that operates within a modern combi boiler makes it a lot easier to recapture heat energy that is produced by the boiler but would otherwise be lost via the flue along with waste gases and condensate.

This new development means that almost all new gas Combination boilers are SEDBUK A-rated, the highest possible efficiency rating available in the UK. Around £300 a year could be saved if you made the move from an older non-condensing G-rated Combi Boiler to a new and improved condensing combi boiler. That’s an efficiency saving of around 30% - a huge improvement.

Finding a spare heating part for an older boiler becomes much trickier over time as boiler ranges become discontinued and new boilers and parts are released. New boilers need less maintenance any way but if they do the parts are always readily available

For the most part new combi boilers last upwards of 10 years, so you will soon recoup the majority of money that you have spent on a new boiler system. New boilers tend to be covered by fairly extensive boiler warranty periods too, so you have added peace of mind that if anything goes wrong with your system you are in a good position to have it sorted out.

Although an expensive purchase, the benefits of a new boiler can be cost effective and can also be well worth it in terms of relieving unwanted stress!

About this article: This article was written by Tom Key, Online Marketing Coordinator at Direct Heating Supplies for use on the Gas Central Heating Blog.

·         Direct Heating Supplies -

Friday, 23 November 2012

Radiators Not Getting Very Hot Downstairs

I went to look at the central heating system of a lady who was complaining that the radiators downstairs were not getting very hot. When the central heating came on the radiators upstairs all got nice and hot straight away, but the radiators downstairs would take an hour before they started to get hot.

I got to the job for eight in the morning so I could see what was actually happening as the heating was set to come on at 730. I looked around the radiators downstairs and only one of the small radiators downstairs was significantly hot. The others were just lukewarm except one which was stone cold. I looked around the radiators upstairs and they were all nice and hot as expected.

Looking in the airing cupboard where the programmer was located I could see that the heating and hot water were both set to be on. I checked the motorised valve and it was in the mid position, 'M'. Being a Drayton MA1 valve there is a sticker on the side which an indicator points to show the position the valve is in. The cylinder thermostat was set to 60°C and so I turned it down and the valve moved to the 'H', central heating position.

I waited for a few minutes and gradually the radiators began to heat up downstairs including the radiator that was completely cold. It appears that the water is going through the cylinder in preference to going round the radiators downstairs. When the hot water was set to be on at the same time as the heating and the cylinder thermostat was demanding hot water the radiators wouldn't heat properly downstairs until the hot water thermostat was satisfied. I checked the settings in the programmer and could see that both the heating and hot water where set to be on from 7am until 10am but in the afternoon the hot water was set to be on 3-5pm and the heating 5-10pm. I asked the lady if she noticed that the problem had only been occurring in the morning which she said it had, but"'assumed the downstairs radiators where working because they had got up to temperature in the morning".

I set the hot water so that it would come on from 6-7am which should be enough as she lives alone and will heat quicker than if on with the central heating. If that wasn't enough on some days the timer could always be put on for an extra hour. The system is fairly old and could most definitely benefit from a powerflush. Unfortunately this is something which she cannot afford at the moment but will probably have done in the summer. It would also be prudent to fit a gate valve to the hot water cylinder return to help balance the system.

Friday, 16 November 2012

Baxi WM No Heating

I was left a message on my answerphone because a customer of mine had no central heating and asked me to attend the next day. He had told me that he could see that the pilot light was lit on his Baxi WM boiler and that the thermostat was turned up. He though it may be the pump as he had a pump seize before.

I attended in the morning, but unfortunately for myself the central heating had come on with the timer and had been working as it should be. The timer had switched off before I arrived and so I switched the heating on and the thermostat up. Everything was working with no obvious issues. I put the hot water on and tested the motorised valve to ensure that it was switching between heating and hot water as it should be. There appeared to be nothing wrong with the system.

The customer asked me to look at something unrelated which I did, and then went back to do a final test before leaving. On the final test I switched the heating on and the motorised valve began to move over but did not open fully enough to activate the micro-switch. I waited a few seconds longer but it still did not cause the boiler and pump to run. I put some pressure on the lever of the motorised valve and it moved further before activating the boiler an pump. I drained the system and replaced the motorised valve and everything has been working well since.

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.