Can someone please help explain this heating behaviour?

[platforminc]

Hi All.

We currently have this heating system whereby there is a cold water tank in the loft, the boiler is on the first floor in one of the rooms, together with another tank next to the boiler and an expansion vessel above the boiler, its a potterton boiler.

Now, the showers are both electric and mains fed, the only hot water taps we have are in the bathroom upstairs, the kitchen and a basin in the utility room.

In the winter the heating programmer was constantly set to on, so we used the thermostat downstairs to control the heating, but whenever the temperature goes lower than 21 it kicks in.

Last week, I changed this from the programmer next to the boiler, the model is a British Gas model UP2. From what I read, it allows you to program the heating/hot water to come on at 3 different schedules, so I did this for the heating only, morning/afternoon and evening.

What we noticed are as follows.

• The radiators upstairs are always boiling hot even outside the heating programmed time. When this happens the hot water light is on.
• The radiators upstairs have always been hotter and faster at getting warm, we attributed this to the fact that the boiler is also upstairs, and I reckon 22mm supply pipes were used instead of 15mm.
• I dont understand what triggers the boiler to kick in for hot water, hence why I didnt change this to programmed time, I just left it at ON.

Is there a reason why the upstairs radiators are very hot when the boiler is only supposed to serve hot water?

Is it a good idea to leave the ot water set to ON or program this to a time, I dont like tampering with the heating system in case I make unintended changes ?


Thanks in advance.

 

[Hugh Jaleak]

Need a few more details on your system I think, but from what you've said, I'd hazard a guess firstly you've got a faulty motorised valve somewhere. This will have the effect of allowing the boiler to heat the radiators when HW only is selected. You're looking for either one of these

or two of these


Secondly, the radiators heating up upstairs faster, is possibly a balancing issue. Basically the water will take the easiest path through the system, so by balancing the rads, you force the water to the furthest parts of the system to ensure all rads get there fair share. (See FAQ's on how to balance the system.)

 

[platforminc]

Thanks for the reply.
In the boiler cupboard, I have a magna clean, a pump and a device called mid position actuator code.

I dont think I have a 2 port motorised valve or maybe its hidden under the floorboards somewhere.

 

[Hugh Jaleak]

Mid position actuator would be a 3 way valve. Some manufacturers versions are renowned for sticking. Can you put some picture up of what you have got?

 

[Madrab]

Do the radiators upstairs cool down when you turn the HW side of the programmer off?

 

[platforminc]

Mid position actuator would be a 3 way valve. Some manufacturers versions are renowned for sticking. Can you put some picture up of what you have got?

Please see th picture

 

[platforminc]

Do the radiators upstairs cool down when you turn the HW side of the programmer off?

Usually when the radiators are hot and I check the programmer, the hot water lights are on. I am sure if I turned it off the radiators will cool down, I never did this as I dont understand the heating system and dont want to tamper with it, not at this lockdown period.

 

[Hugh Jaleak]

I would strongly suspect it is the blue valve at fault here. Is that actuator actually sitting on the brass 'T' shape body with 3 pipes attached to it? Cant tell form the photo.

Your system is what we refer to as 'fully pumped' that is the hot water being produce in the boiler to heat the house is pumped around the system to where it's need. So, from the boiler, the water will flow to that valve, where the flow can split two ways, either to the hot water cylinder, the radiators or both. The valve is electrically operated on commands from the programmer and then two thermostats, one in a room somewhere which will control the radiators, and the other on the hot water cylinder, which will control the hot water.

Problem is highly likely to be this valve has failed, so instead of closing off the flow to the radiators, it has stuck open to the central heating circuit as well as the how water tank. Boiler and pump are still operating on command from the Hot Water system, to heat the cylinder, but some of the flow is also going to the radiators, even though they're switched off electrically.

 

[MeldrewsMate]

You may be able to check if your 3-port valve is stuck.
1. On the LONG side of your blue actuator (mid position actuator) there may be a black plastic button. If you gently press this in you may be able to pull the blue head off the brass valve. If there is no button then you cannot perform this test.
2. Grab the valve shaft and try to turn it one way then the other; it should easily turn about 45 degrees by hand action only.
3. Put the shaft back to the position you found it, and refit the actuator head.

If the shaft doesn't turn EASILY, then put a short spanner on the shaft flats and exercise it left and right - very little force should be needed, and it should loosen-up within a couple of movements....if it was tight then you've found the problem; if it becomes easy to turn after a few cycles then you may have cured the problem.

Test it by having an assistant select HEATING only with the room thermostat set to maximum. The small indicator on the opposite side to the black button should be seen to move fully across its range in about 10 seconds.
Have the operator turn off the heating and turn the HOT WATER only ON (with the hot water thermostat turned high too). You should hear the whirr of the drive motor as it spring returns, and see the same lever returning.

 

[Gasplumber]

Just let everything cool down the turn the hot water only on and feel the A port on the valve and see if it starts getting warm if so replace the valve!
Simple

 

[platforminc]

The actuator is not connected to any valves. It connects to an electrical box which is what controls things.

I found that it has a plastic lever, when I tried to turn it with a little bit of force, I heard the boiler come on, then the thing made a squeaky noise and turned back to it's original position.

At this point, in a bit worried tampering with it.

 

[Gasplumber]

Don’t be worried. I call the brass the valve and the head the actuator. like I said before when it’s all cold turn the hot water only on. Then only 2 pipes at the valve should get hot. The one on the right coming down to the valve is from the boiler and the other 2 are one for heating one for hot water.

99.9% it’s the the motorised valve
Then .1% stat programmer reverse circulation
Just get a new valve and a regin 5 way connector and swap the valve. Try the actuator alone first.

that’s the best I can do without you having a multimeter ect

it’s a Drayton valve too

 

[platforminc]

Thanks mate I really appreciate this.

The valve is that thing that looks like a T junction right?

I will follow you instructions and report back. One thing though, I have a multi meter, however If you want me to use that. Please give me simple layman instructions and I can report back if need be.

 

[Gasplumber]

Yes it’s the valve body. It’s a diverter so diverts water right or left ect or both. Go on YouTube and just search how a y plan works. It will give you lots of info so you’ll understand what your doing more.

 

[oilhead]

Drayton MA1 actuator, notoriously unreliable. Shop around and you will find you can get a complete valve for less than an actuator only. Just use the actuator and start saving up for a new one in 2-3 years time.