Open vented system, No HW, CH works fine, BAXI 80HE boiler shows Dry Fire after every restart

[fandyman]

@Madrab Thanks for your advice. You are 100% correct and I am never planning to touch the boiler and anything that needs a pro. I just find it very difficult to sort a relevant person out that has the right knowledge and is not trying to exploit. I live in south Croydon so if there is someone in the area happy to hear him out.

Attaching the photos of CWSC that feeds the HW cylinder.

 

[fandyman]

Open vent on cylinder, check for any air in there. Could be valve or worse still flow switch on boiler.

Hi @gazfen. Thanks for you reply. I have tried that in the past and although there was some air trapped in there it did not solve the problem.

I think it is something to do with electrics around the valve as it is showing random results from repeated tests. For instance at the moment it only works with CH and HW constantly ON on controller and the A pipe does not get warm but the B pipe gets super warm. The boiler goes into DRY FIRE from time to time. Sometimes cutting power to the whole heating system restores it to this state and sometimes it stays cut off and does not turn on (I mean boiler and pump here).

 

[Johntheo5]

Hi @gazfen. Thanks for you reply. I have tried that in the past and although there was some air trapped in there it did not solve the problem.

I think it is something to do with electrics around the valve as it is showing random results from repeated tests. For instance at the moment it only works with CH and HW constantly ON on controller and the A pipe does not get warm but the B pipe gets super warm. The boiler goes into DRY FIRE from time to time. Sometimes cutting power to the whole heating system restores it to this state and sometimes it stays cut off and does not turn on (I mean boiler and pump here).

So, when you got it "working" by removing/replacing the actuator etc, it still only worked if both HW & CH are both selected and both the roomstat and cylinder stat calling?, if so, with both selected and calling and you then turned down the roomstat, does the boiler stay on and does the valve stay in the mid position?
If you select CH only (with roomstat calling) does the boiler fire up? but still heats both CH & HW, (valve in mid position).
The other mystery is why the flowrate was so low in at least two instances at ~ 2.0LPM (36W) & 5.0LPM (38W). A multimeter would reveal a lot IMO.

 

[fandyman]

So, when you got it "working" by removing/replacing the actuator etc, it still only worked if both HW & CH are both selected and both the roomstat and cylinder stat calling?, if so, with both selected and calling and you then turned down the roomstat, does the boiler stay on and does the valve stay in the mid position?
If you select CH only (with roomstat calling) does the boiler fire up? but still heats both CH & HW, (valve in mid position).
The other mystery is why the flowrate was so low in at least two instances at ~ 2.0LPM (36W) & 5.0LPM (38W). A multimeter would reveal a lot IMO.

@Johntheo5

So, when you got it "working" by removing/replacing the actuator etc, it still only worked if both HW & CH are both selected and both the roomstat and cylinder stat calling?

Not sure it ONLY worked with both HW & CH on but I had to use both at that time and both worked fine (radiators warming up and back to very warm water from shower again). It works now as well with the hot water being very warm and radiators heating up when both are on.

with both selected and calling and you then turned down the roomstat, does the boiler stay on and does the valve stay in the mid position?

The boiler stays on (no calling for heat light but just the on light) and the valve seems to be equally warm on A & B (if that is how you check it stays in the mid position) although the pump shows 31-32W only (the system was warm already though).

If you select CH only (with roomstat calling) does the boiler fire up? but still heats both CH & HW, (valve in mid position).

Yes the boiler fires up and still heats both CH & HW as the valve seems to be equally warm on A & B (if that is how you check it stays in the mid position) although the pump shows 45W now.

In all the above tests I gave about 5-10 minutes before checking the A and B pipes.

I've still got the multimeter checks to do.

 

[Johntheo5]

with both selected and calling and you then turned down the roomstat, does the boiler stay on and does the valve stay in the mid position?

The boiler stays on (no calling for heat light but just the on light) and the valve seems to be equally warm on A & B (if that is how you check it stays in the mid position) although the pump shows 31-32W only. (The system was warm already)

The way to check if its still in mid position is to pull on the lever, if the lever is just loose and floppy then it is in mid position, if its fairly difficult to pull across then its its only open to B, HW.
31/32W means its pumping 0.0LPM which is very strange, but if you do test it by pulling on the lever then you will know whether its just opened to HW or not.

If you select CH only (with roomstat calling) does the boiler fire up? but still heats both CH & HW, (valve in mid position).

Yes the boiler fires up and still heats both CH & HW as the valve seems to be equally warm on A & B (if that is how you check it stays in the mid position) although the pump shows 45W now.

If its in mid position then the same lever test as above will show it loose and floppy.

 

[fandyman]

The way to check if its still in mid position is to pull on the lever, if the lever is just loose and floppy then it is in mid position, if its fairly difficult to pull across then its its only open to B, HW.
31/32W means its pumping 0.0LPM which is very strange, but if you do test it by pulling on the lever then you will know whether its just opened to HW or not.


If its in mid position then the same lever test as above will show it loose and floppy.

The lever was always loose and floppy in all the tests.

 

[fandyman]

Does it mean the 3 port valve actuator is gone?

 

[fandyman]

The HW cylinder is super warm though from yesterday's and this mornings heating. Could it be the reason with rads off and valve stuck in mid position the pump is not pumping and the boiler DRY FIREs as no flow?

 

[Johntheo5]

Does it mean the 3 port valve actuator is gone?

It only means that its in the mid position for whatever reason.

The HW cylinder is super warm though from yesterday's and this mornings heating. Could it be the reason with rads off and valve stuck in mid position the pump is not pumping and the boiler DRY FIREs as no flow?

But if its in the mid position, which we can only assume then both ports are open and the flowrate watts/flowrate should be 45/10.8LPM minimum, and yes, the reason the boiler is not firing is more than likely because of this no flow= Dry fire.

Its very confusing/illogical (re flowrate) as to whats going on, except the gearing is knackered in the MPV and it is actually moving to B only which is not circulating through the coil.
If you remove the actuator again, and making very sure that the valve via your fingers is actually set to B (HW) only, then pump restarted by whatever means you use, go then to check the pump power and turn the valve slowly, manually, through its full travel which will ensure open to B only, then A+B, and then A only, you can then watch the pump power and get a better idea of whats happening.

 

[Madrab]

Or get someone in that's is practiced/experienced with system diagnostics

 

[fandyman]

It only means that its in the mid position for whatever reason.

But if its in the mid position, which we can only assume then both ports are open and the flowrate watts/flowrate should be 45/10.8LPM minimum, and yes, the reason the boiler is not firing is more than likely because of this no flow= Dry fire.

Its very confusing/illogical (re flowrate) as to whats going on, except the gearing is knackered in the MPV and it is actually moving to B only which is not circulating through the coil.
If you remove the actuator again, and making very sure that the valve via your fingers is actually set to B (HW) only, then pump restarted by whatever means you use, go then to check the pump power and turn the valve slowly, manually, through its full travel which will ensure open to B only, then A+B, and then A only, you can then watch the pump power and get a better idea of whats happening.

@Johntheo5 I removed the actuator again and when I manually move the valve from A to B it shows 32W at the beginning (no radiators calling for heat as all thermostat valves closed on them) and the more I turn it increases to 38W and finally reaches 45W (when it reaches B). What is strange is when I try to leave it in mid position I hear a bang on the pipes that start vibrating and it forces it to go to A and the pump shows 32W straight after.

 

[fandyman]

@Johntheo5 Here is the video link: https://drive.google.com/file/d/1wFVQ4dqiT312jDfAsa9uO6XygaBFm1EM/view?usp=sharing

 

[fandyman]

So effectively when all rad valves are closed I cannot set the valve to mid position. Is this correct?

 

[fandyman]

Ahh I now realised you asked me from to do it from B to A not A to B. I can do that and record the pump readings as well.

 

[Johntheo5]

So effectively when all rad valves are closed I cannot set the valve to mid position. Is this correct?

Not sure what you mean by when all the rad valves are closed?, have you got TRVs or smart actuators on them?, sounds lke something has come adrift inside the valve and would suggest getting a new one complete with new actuator and take it from there.