Central heating being weird...

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Lancashire
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Morning all,

I have a bit of an issue which Im hoping some one can help with.

We have just moved into a new house (Built around 2006) it has (From what I have seen in the loft and read online) an open vented system.

There is a water tank in the loft, hot water tank below on the 1st floor in the airing cupboard and a boiler downstairs.
The hot water tank has a heating element however I have switched this off at the wall as we only heat the water once a day from the gas boiler (It stays warm enough through the day)

The boiler has a programmable timer which is preset with some on/off times but we have this set to "Off" all the time and only use the +1 hr for heating the house when it gets really cold (So far not that often).

So to summarise:
1. Emmersion heater should be OFF.
2. Boiler is set to only come on when I press the button (not on timer)

The issues that we have (Which may all be seperate but may all be the symptoms of a bigger issue) are:

1. When only the hot water is on we often get one radiator upstairs warming up (The odd bit is it isnt always the same one!)

2. One radiator doesnt get hot at all, Ever. however I did try to bleed this and noted that when although no air came out as the water drained the opposite side of the rad did warm up.... could this be a dodgy thermostatic valve (it was the opposite side from this that warmed)

3. I came home from work last week at lunch (no one had been in since around 8am) and noted that the boiler was on and one rad was heating up... the programmable timer showed that the boiler was set to off.
mostly worried about this because of the cost, if its comming on on its own and heating an empty house its wasting gas and my money!

4. Last night I heard what sounded like the water tank pumping water, went through to check and sure enough hot pipes (this was at around 1am) checked the boiler - not on.
Checked the immersion switch - still off.
Finally randomly flicked a switch on the top of something (Dunno what it was) from automatic to manual and back again and the pumping noise stopped...
Where did that hot water come from?

Im pretty sure that the immersion is not operating, and I know the boiler had not been running (it was about 1 hour before this though for the central heating)

Im worried that some where we are wasting a lot of gas/electric or that the plumbing is buggered up...

I have uploaded a picture of the airing cupboard (the thing that I randomly flicked was the white box on the right (well one of them) hope thats helpfull!


Any advice would be appreciated.

Thanks.
 
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There is a water tank in the loft, hot water tank below on the 1st floor in the airing cupboard and a boiler downstairs.
Only one tank in the loft?
Make and model of boiler would be helpful

The hot water tank has a heating element however I have switched this off at the wall as we only heat the water once a day from the gas boiler (It stays warm enough through the day)
The electrical heater, in the top of the tank, is only intended for emergency use - when the boiler has stopped working.

The boiler has a programmable timer which is preset with some on/off times but we have this set to "Off" all the time and only use the +1 hr for heating the house when it gets really cold (So far not that often).
That's OK at the moment, but you will need to set some times when it starts getting colder. What make make/model programmer is it? Do you have a wall thermostat, if so make and model, please.

When only the hot water is on we often get one radiator upstairs warming up (The odd bit is it isnt always the same one!)
You have two motorized valves (HW and heating). The heating valve may be leaking internally, so water can circulate even when the valve is off. You can check by feeling the pipes.

The reason for it being different rads could be down to the TRV.

One radiator doesnt get hot at all, Ever.
Yes, this could be a sticking TRV. Set the TRV to Max and then remove the head (usually turn the large knurled nut under the head). This will expose a metal pin, which should go down when pressed and spring up when released. If stuck/sticky, some silicon lubricant will help. If the pin is down and won't come up, try tapping the valve body with a hammer.

I came home from work last week at lunch and noted that the boiler was on and one rad was heating up
This could be due to a frost stat or a frost setting in the boiler.

Last night I heard what sounded like the water tank pumping water, went through to check and sure enough hot pipes (this was at around 1am) checked the boiler - not on.
Are you talking about the pipes which go into the side of the HW cylinder?

Finally randomly flicked a switch on the top of something (Dunno what it was) from automatic to manual and back again and the pumping noise stopped
The two white things are motorized valves (see earlier). It sounds as if one of the valves is sticking.
 
Thanks for the reply!

I have uploaded pictures of the boiler, user manual, Thermostat, and a few other bits and pieces.

In response to your questions:

I only saw one tank in the loft (however I wasnt up there looking for them it was an unrelated job, so maybe I missed one) As for make/model Ill have a look later but I dont remember seeing anything any markings on it it was just a big tank...

As for the explanation about the TRV causing diffrent rads to warm, it could be that.. Ill try switching a few off and see if it moves the one that heats up...
Would he rads heat up if the boiler was supplying too much hot water to the hot tank when the water was on only? I noticed that when faffing last night I knocked the thermostat on the boiler down to 20 degrees... and we got a rad warming this morning when the boiler was supplying hot water...... just wonder if that could be related.
PS. Only realised that I had done this when I got in the 20 degree shower.... bit chilly for my liking!


"Are you talking about the pipes which go into the side of the HW cylinder? "

Yes the pipe to the top was cold, but the ones comming out of the bottom right leading into the loft were hot.

Again, thanks for your reply, sorry for the big blob of text... got to figure out that quote button.. it wasnt working for me!

Im off to bash that sticking TRV... Ill let you know how it goes!

Thanks



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I only saw one tank in the loft (however I wasnt up there looking for them it was an unrelated job, so maybe I missed one) As for make/model Ill have a look later but I dont remember seeing anything any markings on it it was just a big tank
If you have an open vented system, you should have two tanks: large to supply cold water to the HW cylinder and taps; small to feed/top up the heating system. If you only have one tank, you have a sealed system.

Would he rads heat up if the boiler was supplying too much hot water to the hot tank when the water was on only?
No. This will only happen if the white heating valve is not closing properly

I noticed that when faffing last night I knocked the thermostat on the boiler down to 20 degrees... and we got a rad warming this morning when the boiler was supplying hot water...... just wonder if that could be related.
Not connected. The white heating valve is probably passing water when it's supposed to be closed. You can tell this by feeling the pipe either side of the valve.

Yes the pipe to the top was cold, but the ones coming out of the bottom right leading into the loft were hot.
The pipe at the very top, next to the immersion heater, is the hot water supply to the taps. The branch going up into the loft is a safety vent pipe. You will see the other end hanging over the cold water cistern in the loft.

The pipe at bottom left is the cold water feed from the cistern in the loft.

The two pipes on the right are the flow from the boiler (via a white motorized valve) and the return to the boiler. They are connected internally by a large coil of copper pipe. The water passes through this and so heats up the water in the cylinder.
 

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