All Radiators Heat Up With Hot Water On Sometimes Only Bathroom One

All Radiators Heat Up With Hot Water On Sometimes Only Bathroom One 

Hi all,
I'm not a central heating engineer, can just about tell the difference between  a hot and cold tap Having having trouble working out why my central heating is doing what it does. I hope someone can help me fathom it out.
I have a Baxi Solo 18 HEA boiler, which is about 2 years old and had little use, wood burner. 
Boiler has a wireless link to a thermostat in the hall and a thermostat (manual ) connected to the hot water cylinder . I've used Fernox F5, not power flushed, just ran it on heating cycle for about a week, drained system down and refilled, bled radiators. Used F5 to clear out any sludge that might be in the system.

These are some of the symptoms, on the control panel I switch on both heating and hot water options on continuous setting. System comes on all radiators heat up, burner goes off after about an hour.

The other night I had a hot bath, turned heating and hot water on together, continuous setting.for about  1.5 hours then switched itself off. Now ordinarily what happens after it switches off and I turn on again, only the bathroom radiator gets hot all the others remain cold.
On this occasion I filled the bath up with hot water, once full, as I intended to have a hot long soak and would prefer the bathroom radiator to be warm. I turned the boiler back on and to my surprise bathroom radiator heated up, as well as the others I think.

Today I tried turning the thermostat on the hot water tank to minimum and ran the heating and hot water options on the control panel to see what happened, only the bathroom radiator got hot, the pump is close to it under the bathroom floor, the main boiler is below the bathroom.
I then turned the hot water cylinder thermostat up about a 1/3 turn then all the radiators started to heat up.
As I say ordinarily if I switch system on in morning continious setting, it will run for say 1.5 hours then switches off or burner stops. Later on a bit if start system again only bathroom radiator heats up all others remain cold.
As I say on the control panel I can select heating and hot water together and on continuously, then all the radiators get hot. If I only select heating option continuously then only the bathroom radiator gets hot..... Um
Cheers,
Peter.     https://amymaytrust.com/

What happen if you turn on JUST the heating, not the hot water?

How is it plumbed? S plan, Y plan etc?

It's not something simple like the radiators have thermostatic valves on them and they are set to minimum, when the house and system is cold you get heat out of them once there is a bit of heat in the system they won't come on, the reason the bathroom one comes on is maybe it is the one nearest the boiler so no TCV fitted.

Of course this is just a wild stand in the dark.

It sounds like you have heating and hot water controls the wrong way around. Turning up the cylinder stat should have no effect on the heating.

The bathroom radiator getting hot all by itself could be due to one of two things. Some systems are designed with the bathroom rad tee'd off the hot water primaries going to the cylinder, so  that if hot water is turned on, the radiator gets hot and warms your towels. The other reason might be gravity flow, the radiator is above the boiler, hot water rises and displaces the water in the radiator, even though the heating circuit is not switched on.

roys said:

It's not something simple like the radiators have thermostatic valves on them and they are set to minimum, when the house and system is cold you get heat out of them once there is a bit of heat in the system they won't come on, the reason the bathroom one comes on is maybe it is the one nearest the boiler so no TCV fitted.

Of course this is just a wild stand in the dark.

Click to expand...

Only one radiator has a thermostatic valve fitted.

ProDave said:

What happen if you turn on JUST the heating, not the hot water?

How is it plumbed? S plan, Y plan etc?

Click to expand...

Selected just the heating option, boiler came on then burner ignited. Bathroom radiator got nice and hot all other radiators cold. Water has heated up hot. Boiler burner switched off after about 40 minutes  though boiler pilot light still on. I'll try just selecting the hot water option and will get back to you about the result.

Cheers.

ProDave said:

What happen if you turn on JUST the heating, not the hot water?

How is it plumbed? S plan, Y plan etc?

Click to expand...

Selected just the heating option, boiler came on then burner ignited. Bathroom radiator got nice and hot all other radiators cold. Water has heated up hot. Boiler burner switched off after about 40 minutes  though boiler pilot light still on. I waited a while then selected just the hot water option. At first nothing happened, boiler pilot light didn't even come on. So turned up the thermostat on the hot water tank. Then boiler came on and burner ignited all radiators heating up.

All the radiators are getting quite hot though bathroom one seems luke warm.

I quickly Googled S plan and Y plan and watched a couple of YouTubes. Think can rule out a 3 port valve as think that is manual, doesn't require an electronic programmer.

These valves for the S and Y plan, if I take up the floorboard where the circulation pump is.  I assume I will find the valves close by the pump and can then determine if S or Y plan?

Cheers  Ps Also looked at manual could,t see any indication if S or Y plan.bathroom radiator definitely luke warm all others getting nice and hot

Rob_the_rich said:

It sounds like you have heating and hot water controls the wrong way around. Turning up the cylinder stat should have no effect on the heating.

The bathroom radiator getting hot all by itself could be due to one of two things. Some systems are designed with the bathroom rad tee'd off the hot water primaries going to the cylinder, so  that if hot water is turned on, the radiator gets hot and warms your towels. The other reason might be gravity flow, the radiator is above the boiler, hot water rises and displaces the water in the radiator, even though the heating circuit is not switched on.

Click to expand...

OK thanks.

Ed51 said:

Selected just the heating option, boiler came on then burner ignited. Bathroom radiator got nice and hot all other radiators cold. Water has heated up hot. Boiler burner switched off after about 40 minutes  though boiler pilot light still on. I waited a while then selected just the hot water option. At first nothing happened, boiler pilot light didn't even come on. So turned up the thermostat on the hot water tank. Then boiler came on and burner ignited all radiators heating up.

All the radiators are getting quite hot though bathroom one seems luke warm.

Click to expand...

I would first check the 3 port valve. With just heating selected, the hot water should not have heated up. likewise with just hot water selected, the radiators should not have heated up

With such a bizarre fault, I have to ask, has it EVER worked properly?  It almost sounds like the outputs from the programmer are connectd the wrong way round, except for the fact the tank thermostat seems to be connected to the hot water output.

My standard questions in such circumstances:

1. Has anything recently been "changed" on the heating system?

2. Has it ever worked properly?

3. What happens if you turn the heating off, the water on and turn up the tank stat?

4. What happens if you turn the water off, the heating on and turn up the room stat?

NB: don't do 3 and 4 "back to back" as you need to do this when all the rads are cool.

OK thanks people will get back to you all sometime Sunday.

ProDave said:

I would first check the 3 port valve. With just heating selected, the hot water should not have heated up. likewise with just hot water selected, the radiators should not have heated up

With such a bizarre fault, I have to ask, has it EVER worked properly?  It almost sounds like the outputs from the programmer are connectd the wrong way round, except for the fact the tank thermostat seems to be connected to the hot water output.

Click to expand...

OK thanks, I'll get the floorboard up over the circulation pump and see if valves, will take photo and get back to forum.

Murdoch said:

My standard questions in such circumstances:

1. Has anything recently been "changed" on the heating system?

2. Has it ever worked properly?

3. What happens if you turn the heating off, the water on and turn up the tank stat?

4. What happens if you turn the water off, the heating on and turn up the room stat?

NB: don't do 3 and 4 "back to back" as you need to do this when all the rads are cool.

Click to expand...

1 before Christmas we added a radiator to the kitchen extension.

Had the boiler installed 2+ years ago, shortly after got a big woodburner and we put an electrical immersion element into hot water tank.

cylinder. Boiler has had very little use, was all properly installed, signed off etc. As I say has had literally very,very little use, actually switched off electricity supply to it for a year or so.

3+4 will do this on Tuesday and get back to forum, as said above, will also lift floorboard above circulation pump to see what valve and photo.

Cheers. 

Does the wood burner also heat he radiators?  If so, how is it connected to the system?

This has got me thinking. Is this a conventional hot water cylinder? or a thermal store?

Or is their a neutraliser to combine the stove and boiler output?

ProDave said:

Does the wood burner also heat he radiators?  If so, how is it connected to the system?

This has got me thinking. Is this a conventional hot water cylinder? or a thermal store?

Or is their a neutraliser to combine the stove and boiler output?

Click to expand...

Wood Burner is a stand alone, and as far as I understand, a conventional hot water cylinder.

Thanks.

maybe one of the rads is used as a heat dump?

Murdoch said:

My standard questions in such circumstances:

1. Has anything recently been "changed" on the heating system?

2. Has it ever worked properly?

3. What happens if you turn the heating off, the water on and turn up the tank stat?

4. What happens if you turn the water off, the heating on and turn up the room stat?

NB: don't do 3 and 4 "back to back" as you need to do this when all the rads are cool.

Click to expand...

Question 3 = hot water option continious setting all radiators scalding hot except bathroom which is cold. Ran hot water tap for a few minutes water luke warm, before swiching system and hot water option on. Set thermostat on hot water tank to 60 degrees C
Question 4 = Turned heating on, continious setting and hot tank thermostat still set at  60 degrees C. Bathroom radiator scalding hot all other radiators cold.Burner turned off after about 30 minuters boiler pilot light still on, turned on hot tap scalding hot.
 

sounds like connections to controller are cross wired

Andy™ said:

sounds like connections to controller are cross wired

Click to expand...

The important un answered question is "has it EVER worked properly?"

If not I tend to agree the wiring has been done wrong but it is a very strange fault to occur if it previously worked okay and nothing has been touched.

Andy™ said:

sounds like connections to controller are cross wired

Click to expand...

If that's the case, would it be a job I could, legally do myself? Or would I need to have a Gas Safe registered, Corgi whatever, fully qualified, up to date, heating engineer to fix it and sign it off. Attach photo of circulation pump and the only valve near it.

Cheers.

actually, it may be wired correct the the 3 port valve in the wrong way