Trying to fix a problem on a s-plan heating system. Boiler is working fine, only problem is heating and hot water are not working at the same time. If we turn the heating off, then hot water starts working. Looks like a problem with one of the 2-port valves. The system has got a 22mm 2-port valve on hot water and the lever on the valve goes back to auto when i move it to manual. On the heating side is a 28mm 2-port valve and the lever is moving freely and doesnt go back to auto itself. Can anybody advise please how to find out whats the problem. Thanks
problem on a s-plan heating system
- Thread starter victor71
- Start date
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When you say that the lever on the hw 2-port isn't staying in manual, it may be that this valve is jamming, or the rubber ball inside is swollen/damaged.
In this case, the valve isn't opening fully. When the hw is sharing the flow with the heating, there isn't sufficient flow through the hw valve, but when the heating is off, there is greater pressure to force the flow through the faulty hw valve and heat the cylinder.
In this case, the valve isn't opening fully. When the hw is sharing the flow with the heating, there isn't sufficient flow through the hw valve, but when the heating is off, there is greater pressure to force the flow through the faulty hw valve and heat the cylinder.
Has it always been like this, or just started?
If it's always been like this it could be that the water flows around the heating circuit, because it has a lower resistance than the flow to the hot water cylinder. Is there a valve on the circuit between the hot water cylinder and boiler that has been closed down too much?
As this is an 'S' type there will likely be a manual by-pass somewhere. Is it is open more than it should be and taking too much of the flow, leaving insufficient for the radiators and hot water?
When a motorised valve is off, ie no electrical supply to it, then there will be a resistance as the lever is moved to manual. It should return to auto when you let go of the lever (unless you latch it in the manual position)
When the valve is powered up there should be no resistance if you slide the lever from auto to manual, and the lever will probably stay where you leave it.
If it's always been like this it could be that the water flows around the heating circuit, because it has a lower resistance than the flow to the hot water cylinder. Is there a valve on the circuit between the hot water cylinder and boiler that has been closed down too much?
As this is an 'S' type there will likely be a manual by-pass somewhere. Is it is open more than it should be and taking too much of the flow, leaving insufficient for the radiators and hot water?
When a motorised valve is off, ie no electrical supply to it, then there will be a resistance as the lever is moved to manual. It should return to auto when you let go of the lever (unless you latch it in the manual position)
When the valve is powered up there should be no resistance if you slide the lever from auto to manual, and the lever will probably stay where you leave it.
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it was working fine before, only had this problem for few weeks. I cant see any by-pass valve in the system. and we havent adjusted anything. if I turn heating off and hot water on, then there is no resistance in the lever on hot water valve . that means valve is ok. Still cant find whats the problem.
picasso, the OP said that the 28mm valve is on the radiators. Not the hot water. The water has a 22mm valve.
victor71, when the hot water and heating are both on and calling for heat, is the hot water valve actually open, or does it only open when the heating is off?
victor71, when the hot water and heating are both on and calling for heat, is the hot water valve actually open, or does it only open when the heating is off?
STEM
Hot water valve doesnt open when both heating and hot water are on, it opens when only hot water is on and heating is off. Thanks for replies .
Hot water valve doesnt open when both heating and hot water are on, it opens when only hot water is on and heating is off. Thanks for replies .
I'm assuming you checked this when the hot water cylinder thermostat was calling for heat (ie 'on') and the radiators were also on. If so, the problem seems to be the electrical supply to the hot water valve, or rather, the lack of it.
Your programmer will provide a live supply conection (called hot water 'on') that should go to the hot water cylinder thermostat. At the thermostat the live is switched on to the motorised valve when the temperature of the hot water cylinder requires it.
For some reason, the live isn't there when the radiators are on. This is strange, because you say it used to work, has anything been changed recently?
The next stage is to find out what happens to the missing live (or possibly neutral). However you will need a multimeter, and be able to use it safely to proceed. Can you do this?
Your programmer will provide a live supply conection (called hot water 'on') that should go to the hot water cylinder thermostat. At the thermostat the live is switched on to the motorised valve when the temperature of the hot water cylinder requires it.
For some reason, the live isn't there when the radiators are on. This is strange, because you say it used to work, has anything been changed recently?
The next stage is to find out what happens to the missing live (or possibly neutral). However you will need a multimeter, and be able to use it safely to proceed. Can you do this?
Hi, victor71 - did you fix the problem? I have the exact same issue at the moment (hw only heats when turned on itself, not when ch turned on). Like you no recent changes to system like yours.
Not sure if related, new boiler put in 2 yrs ago and get vibrating noise from time to time. Heating eng could not see a problem
Not sure if related, new boiler put in 2 yrs ago and get vibrating noise from time to time. Heating eng could not see a problem
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