Boiler heating problem

Prezatch

We have a problem in our apartment (2 years old) where the boiler seems to be heating fine (it's a condensing boiler) and the plumber has been out to check it and said it's grand. But the water in the taps is not hot. My guess is that it's not getting to the tank. I'v had the boiler on now for around 2 hours, the light above the flame is coming on for around 10-15 seconds every few minutes and then shutting down. There's a good bit of heat coming off it but none of the piping in the tank room is hot. The pipe coming into the tank at the top is not as cold and the water in the taps is slightly lukewarmish. The boiler used to heat the water in no time. I'm a bit concerned the way the light on the boiler doesn't light up above the tap symbol too, only the rad symbol. The rads also aren't heating. The expansion vessel appears to just have air in it. The pressure on the gauge in the tank room is around 1 bar. Also, normally the pressure on the boiler is just above 1 bar (dropped from around 1.3 in the last few months). It jumps up about half a bar or more when it's turned on, which is why it's high in the pic. Any suggestions??

I have attached the below pictures of the boiler and the tank's room:

http://student.dcu.ie/~wardh2/DSC00864.JPG
http://student.dcu.ie/~wardh2/DSC00865.JPG
http://student.dcu.ie/~wardh2/DSC00866.JPG
http://student.dcu.ie/~wardh2/DSC00868.JPG
http://student.dcu.ie/~wardh2/DSC00870.JPG
http://student.dcu.ie/~wardh2/DSC00871.JPG
http://student.dcu.ie/~wardh2/DSC00873.JPG
http://student.dcu.ie/~wardh2/DSC00874.JPG

youtheman

Hard to diagnose the problem from here.

If you look at picture 866 and specifically the bottom row of lights you see:

1. the light on the bottom left is indicating the system is switched on
2. the second light with the tap symbol is indicating THAT THE SYSTEM IS NOT HEATING THE HOT WATER TO THE TAPS.
3. the third light with the radiator symbol is indicating that the system is heating the central heating circuit (to the radiators).
4. the flame symbol on the right is indicating that the boiler is firing.

So assuming that nobody has frigged with the various valves, I'd check to see if there is a thermostat on the side of the cylinder and make sure somebody hasn't turned it down (this could be the reason that the system is not heating the water).

On picture 868 there appears to be an actuated (zone) valve under the red tap. Do you know if it is open or closed?

slavetothegrind

Sounds like your pump failing, again hard to say for sure.

The motorised valve you mention should have a manual bypass lever.

Ya need a plumber to take a looksee.


While he/she is at it ask them to sort out the expansion vessel, it seems to be supported only by the 3/4" copper pipe underneath. When they fail they fill with water, get heavy and need support or will cause leak/flood if pipework damaged.

Amazing how common that is, unsupported vessels.

Joey the lips

This is a hard one for me to tell from here. I am curious. If you ,had a plumber out did you not explain the hot water problem. Your right it is strange considering the system is pressurised I am wondering if the primary return was plumbed correctly but if it was not it would never work

anyway this is either sonetime simple like your time clock is not heating the water(Which I doubt it) or it is a serious issue irequiring the plumber you had to sort it.

As you mentioned your boiler is firing getting up to temperature and shutting off again, this would suggest it's not a boiler issue, it less likely(but still possible) to be the pump, if it was defective then normally the boiler would be over heating and you wouldn't see the pressure guage increasing when the boiler fires, this fault is normally a circulation issue, i would manually open the hot water zone valve(silver box with lever by cylinder) if you still have no movement i would have the boiler checked to see if there is a central heating filter and if it's blocked. As Thats a unvented cylinder only override the hot water two port valve to check it's calling for heat and to open up the hot water circuit, don't leave it open. Also as Slavetothegrind mentioned get the expansion vessel sorted, it's on the hot water draw off and it will fail(in my experience) as they are designed for the cold mains feed side, Gary.

johndel

thats a potterton or baxi system ie boiler and bullitproof first check motorised valve has power usually by cylinder stat ,then check you balancing valve which is a normal gate valve this should be open about a turn and a half

Prezatch

Hi guys thanks for all the replies. Some other information is that we've had 3 plumbers and a heating specialist company out to look at this. 2 of the plumbers thought it was that air was caught in the system. They removed the rads, emptied them and then turned on the water for about 20 seconds on both sides of the rad piping. Then refilled the system to get the pressure back up. It worked for a few days after the first guy did this. We had him back to do the same thing again but it didn't work then. Second plumber tried the same thing awhile later and made no difference either.

The last plumber thought it was the pump, so he replaced it. That made no difference so he put the old one back in. The pressure on the boiler dropped over night, we refilled the system to get the pressure back up. We then had Dyno Rod in the next day and they said there was nothing they could do as the pressure was staying up now. And we've had heat for around 10 weeks. Pressure was at 1.3 bar and has dropped to 1.1 bar now. But it was definitely not as efficient at heating the water as it used to be, ie. we had to leave the boiler on for 2 hours in the morning for 2 short showers.

Also, we recently repainted the hall of the apartment and had the rads off the wall for a few days, back on now. Thinking maybe air got into the system?

youtheman wrote: »

2. the second light with the tap symbol is indicating THAT THE SYSTEM IS NOT HEATING THE HOT WATER TO THE TAPS.
On picture 868 there appears to be an actuated (zone) valve under the red tap. Do you know if it is open or closed?

My housemate says that light never used to come on anyway, even when it was heating. Are you taking about the red tap in 868 or the grey box thing? The tap is closed.

gary71 wrote: »

i would manually open the hot water zone valve(silver box with lever by cylinder) if you still have no movement i would have the boiler checked to see if there is a central heating filter and if it's blocked.

Do you mean the tap beside the box or something in the box?

As Thats a unvented cylinder only override the hot water two port valve to check it's calling for heat and to open up the hot water circuit, don't leave it open.

hot water two port valve?

johndel wrote: »

thats a potterton or baxi system ie boiler and bullitproof first check motorised valve has power usually by cylinder stat ,then check you balancing valve which is a normal gate valve this should be open about a turn and a half

Yep it's a potterton. I'm afraid I don't understand the rest of your instructions

johndel

the motorised valve is the silver box with honeywell ritten on it it has a slidy button on it auto and manual their is a stop point while in manaul its a little nibof metal,that motorised valve should be controled by a cylinder stat .on the other pipe from the central heating going into the cylinder their should be a gate valve called a balancing valve make sure it is open to no to much though ,is their an air vent on the heating pipework if not you may need to open up one of the pipes going to the cylinder to check if their is air in the pipes their is an auto air vent on top of the pump in the boiler to

MiniGolf

JoeyD wrote: »

My housemate says that light never used to come on anyway, even when it was heating. Are you taking about the red tap in 868 or the grey box thing? The tap is closed.

You have a Potterton System boiler (not condensing btw!) A system boiler is basically a combi boiler with the hot water side taken out. The light for the hot water (tap symbol) is not used in this boiler.... it is just there for the combi version so it will never light:). If the red tap you refer to in 868 is closed and is on the return from the coil (for hot water) that is your problem. Try opening it about 1 - 1 1/2 turns.

Just had a look on the Santon website for the instructions on the cylinder....... the red valve in 868 IS the valve to regulate the flow on the return from the coil so if it is closed you will never get hot water. There still may be a valve/thermostat fault but try opening the valve as I said by 1 to 1 1/2 turns first and let us know.
You didn't say in your posts but are your rads working??
Also you have the boiler turned up much too high..... should only be about half way to give you the 60/70 lights lit at most.

Sorry, zone valve and two ports are the same thing;).

If you open the valve beside the the cylinder via the lever and the gate valve at the cylinder is open as MiniGolf wrote, then you will have no restriction around the hot water circuit and you should have movement and your boiler should stay on, if you find that afterwords you still have the boiler getting up to temperature quickly and shutting off, then the boiler thermistor could be defective giving a false temperature reading(a boiler engineer would need to check) or the heat isn't leaving the boiler quickly enough indicating a circulation issue, this could be sludge, air, dirty boiler filter, blocked heat exchanger etc.. but a good boiler engineer should be able to identify the reason, Gary.

Prezatch

MiniGolf wrote: »

There still may be a valve/thermostat fault but try opening the valve as I said by 1 to 1 1/2 turns first and let us know.
You didn't say in your posts but are your rads working??
Also you have the boiler turned up much too high..... should only be about half way to give you the 60/70 lights lit at most.

Ok i will give this a try later and turn down the boiler. The rads aren't working (my first post). Yourself and Johndel seem to be talking about the same thing.

gary71 wrote: »

If you open the valve beside the the cylinder via the lever

You'll have to point that one out to me in one of the pics, do you mean the yellow lever on the wall at 873?

Thanks

The yellow one is your gas isolation valve, the picture 868 shows a two port zone valve http://www.plumbnation.co.uk/site/honeywell-v4043b-22mm-2-port-valve/ and a wheel head gate valve http://www.plumbnation.co.uk/site/hep2o--gate-valve/.

Prezatch

Ok great, thanks for clearing that up. I'll give it a shot later.

Prezatch

johndel wrote: »

the motorised valve is the silver box with honeywell ritten on it it has a slidy button on it auto and manual their is a stop point while in manaul its a little nibof metal,that motorised valve should be controled by a cylinder stat .on the other pipe from the central heating going into the cylinder their should be a gate valve called a balancing valve make sure it is open to no to much though ,is their an air vent on the heating pipework if not you may need to open up one of the pipes going to the cylinder to check if their is air in the pipes their is an auto air vent on top of the pump in the boiler to

The motorised valve is warm so I presume it is being powered ok. There is no cylinder stat though, the pipe runs from the cylinder through the valve and into the wall. It is set to auto. The other side says manual open and has the nib of metal you were talking about. Is it correct to have it on auto?

As for the balancing valve I'm not sure if it was fully open or fully closed. I turned it fully anti-clockwise and then back 1 and half turns so hopefully it's open 1 and a half now.

Things are pointing towards a circulation issue again.

JoeyD

JoeyD wrote: »

The motorized valve is warm so I presume it is being powered OK.

no, you need to push the arm along to the end of it's travel then you will find a little catch, you can push the arm into it, this will leave it manually opened, which will prove it's open and not preventing circulation,

JoeyD wrote: »

There is no cylinder stat though.

as it's a unvented cylinder, it must have a cylinder stat it is probably under the gray box where the cables are going to on the side of the cylinder, if you manually open the zone valve you don't have to worry about the cylinder stat but next time you have someone out get them to explain the system components

JoeyD wrote: »

As for the balancing valve I'm not sure if it was fully open or fully closed. I turned it fully anti-clockwise and then back 1 and half turns so hopefully it's open 1 and a half now.

i tend to turn them all the way clockwise to the closed position then count the turns anti clockwise to get a idea how much restriction there is, personally i would open it fully( as it is now), because the reheat time for the cylinder is really quick so if the cylinder was robbing all the heat it would get up to temperature fast then switch off the zone valve.

JoeyD wrote: »

Things are pointing toward a circulation issue again.

if the zone valve and the wheel head gate valve are open then there is nothing between the cylinder and the boiler and you should get movement, if the boiler still fires gets up to temperature and you can feel the heat at the flow pipe on the boiler,then something is preventing circulation, it's not the pump, i would be surprised if it were air, i tend to get this problem with dirt in the heat exchanger or boiler filter(if one fitted) , Good luck, Gary

Prezatch

Just an update, we had a good plumber in who had it sorted inside an hour. He did a lot of tweaking and said there wasn't enough pressure in the system. Also as none of the radiators were on there wasn't enough circulation. But it's all working now, piping hot!