Remeha - one radiator since service

[ianmcd]

it is possible that you have an air lock, it is unusual in a sealed system but have seen it happen, more so if PE pipe has been used and hasnt been clipped and run properly, if you do one rad at a time and it is air you will hear it and just vent it by bleeding the rad in the normal way then top the pressure up using the filling loop.

 

[chriselevate]

Thanks Ian. I agree with your comment, I'm pretty sure I don't have an air lock on my system as I've done what have been suggested so far and I've vented every single radiator and all I get is water and no hear. I haven't heard any "glugging" from the air moving so I'm pretty sure my close system is full of water and no air. So you mention "PE pipe" - I'm not too sure what you mean by this. What else would you suggest I do/try? Thanks.

 

[ianmcd]

did all the radiators heat up individually when you tried them ?

 

[chriselevate]

I've had mixed results to be honest. Some did and some didn't. Any thoughts? My example I'm working with is the one marked in blue on the downstairs diagram. I can't get that one hot at all.

 

[terryplumb]

so the " blue " rad NEVER gets hot ,no matter what you do ,is that correct ? remove the trv head on that rad ,and there is a small pin in the centre of the metal valve body. that pin should move freely up and down ,only a few millimetres.and pulled up it is open. I suspect that valve pin is stuck down ( closed ) and you have no flow thru that rad. also think the vertical drop to that trv may hold air ,as you can't vent it .the water only going in via the return. try and let us know. with regard to the towel rad I suspect it does not have a trv ,just two wheel head . I suspect the one you used to turn it off may be the lockshield. may be totally wrong but it certainly appears to me to be balance / air / restriction related.

 

[chriselevate]

That's right, the "blue" rad NEVER gets hot not matter what I do. And I've given the small pin a tap and made sure that it's up/open so the radiator is "getting/receiving" the water but this hasn't fixed it either. I think it's worth considering that the vertical drop to it could be holding air. I'm right in assuming that is all of my TRV's are set to off, the boiler should have a VERY hot Feed and Return set of 22mm's attached to it? In other words, it should then just be pushing CH water (under my floorboards) round the system and back?

If there is an airlock in something like the vertical drop, how would I move it/vent it? I have a horrible feeling that it's not this but if it is it'd be good to eliminate this next. IF it's not this, do you know what else it could be/what I'd be trying next?

Yes, the towel rail has no TRV valve on it, just two wheel heads. So the theory here is that if I turn one side off, it too should go cold after it's cooled down over time.

 

[D_Hailsham]

Also worth noting...
1. The Flow is ALWAYS extremely HOT - even when the return is lukewarm.
2. When running the heating system the hot water seems to raise a LOT in temperature.
3. There are no fault codes on the boiler.
4. The pressure is fine.

1. There should only be a 10C to 20C difference between flow and return temperatures. You can find out what they are as follows:

Press the + button and you will see t1, then a number, e.g 67. This is the flow temperature
Press + again and you will see t2, then a number, e.g 44. This is the return temperature.
Press + again and you will see t3, then a number, e.g 55. This is the hot water temperature.
Press + again and you will see t4, then --. This is the outside temperature, which requires an outside sensor. Don't worry about it.
Press + again and you will see FL, then, e.g 7.6. This is the ionisation current. Not important
Press + again and you will see nF, the, e.g 22. This is the fan speed, which determines the boiler output, It will vary between 13 and 50 (CH) or 67 (DHW).
Press + again and you cycle back to t1.
Press R to clear.​

It would help to know what t1, t2, t3 and nF are under different conditions.

2. Do you mean the hot water out of the tap is hotter when the heating is on, than when the heating is off? If so this would suggest that the diverter valve is not working correctly. (You should only be able to have CH or DHW, not both at the same time.)


3. If only one radiator is working the boiler will automatically modulate down to minimum output (nF=13). If the flow temperature continues to rise, the boiler will turn off for a few minutes until the water temperature has dropped a few degrees. It then relights and the cycle starts again. The pump continues to run for a few minutes while the boiler is off.

4. I see from the pic that the boiler only displays 1 dot (off) or 2 dots(on); it also displays error codes. I think this is useless, so I have changed the display so it shows the status codes. You can do this by changing parameter P6 to 1. Instructions are in the 2-page Short User Guide.

You can find the status codes in sections 2.9.5 and 4.3 of the Installation Manual.

 

[terryplumb]

re bath rad ,closing either valve will stop rad from heating, however the valve connected to the flow is the one you should use. the other one is the lockshield. every rad has one , each one is set at a particular open position ,and vary from rad to rad. the. l/ shields are used to balance the CH system ,which means every rad is getting it's fair share of the hot flow ,and are set at the time of installation. so if you go changing their set positions you upset the balance. re boiler...if you close EVERY rad off by their trv's the heat generated by the boiler has to be dispersed ,and the pump has a closed circuit so the internal by pass ( or external if applicable ) should give the pump an open circuit . don't get too hung up on the temps between flow and return. your problem is not the boiler but circulation / distribution of the hot water the boiler is obviously producing.
1. the circulator ( pump), moves the water around.
2. air in the system can hinder this.
3. radiator valves { closed ,when you may think they are open ) prevent it.
4. balance ,so every rad gets its equal share.
5. physical obstructions , broken valves ,blocked pipes / rads. sludge etc.

regards terry

 

[chriselevate]

Cool, thanks guys.
Not really sure what tests to do next? I guess my main test is to try to get the one marked in BLUE on my diagram working and when that works I can the reintroduce the others?

Ok... the Boiler starting readings are as follows:
t1, then a number, e.g 67. This is the flow temperature. 55
t2, then a number, e.g 44. This is the return temperature. 56
t3, then a number, e.g 55. This is the hot water temperature. --
t4, then --. This is the outside temperature, which requires an outside sensor. Don't worry about it. Yes it's --
Press + again and you will see FL, then, e.g 7.6. This is the ionisation current. Not important. 0.0
Press + again and you will see nF, the, e.g 22. This is the fan speed, which determines the boiler output, It will vary between 13 and 50 (CH) or 67 (DHW). 0

After it's been on for 5 mins of CH the readings are as follows:
t1, then a number, e.g 67. This is the flow temperature. 71
t2, then a number, e.g 44. This is the return temperature. 69
t3, then a number, e.g 55. This is the hot water temperature. --
t4, then --. This is the outside temperature, which requires an outside sensor. Don't worry about it. Yes it's --
Press + again and you will see FL, then, e.g 7.6. This is the ionisation current. Not important. 0.0
Press + again and you will see nF, the, e.g 22. This is the fan speed, which determines the boiler output, It will vary between 13 and 50 (CH) or 67 (DHW). 0

After 10 minutes of CH:
t1, then a number, e.g 67. This is the flow temperature. 78
t2, then a number, e.g 44. This is the return temperature. 77
t3, then a number, e.g 55. This is the hot water temperature. --
t4, then --. This is the outside temperature, which requires an outside sensor. Don't worry about it. Yes it's --
Press + again and you will see FL, then, e.g 7.6. This is the ionisation current. Not important. 0.0
Press + again and you will see nF, the, e.g 22. This is the fan speed, which determines the boiler output, It will vary between 13 and 50 (CH) or 67 (DHW). 0

I notice that nF is NOT "between 13 and 50 (CH) or 67 (DHW)" as you mentioned. Is this the issue?

Update....

Switched on the rad marked in the diagram as RED and I got this...
t1, then a number, e.g 67. This is the flow temperature. 68
t2, then a number, e.g 44. This is the return temperature. 66
t3, then a number, e.g 55. This is the hot water temperature. --
t4, then --. This is the outside temperature, which requires an outside sensor. Don't worry about it. Yes it's --
Press + again and you will see FL, then, e.g 7.6. This is the ionisation current. Not important. 8.1
Press + again and you will see nF, the, e.g 22. This is the fan speed, which determines the boiler output, It will vary between 13 and 50 (CH) or 67 (DHW). 15

Update...
Since it's been on, my DHW (out of the tap) has gone about 10-20 hotter. It's BOILING hot right now!

 

[terryplumb]

getting more complicated ,but focusing only on the " blue " rad that never gets hot ,clearly no flow thru that .so if you really want to try to look into that yourself are you prepared to ?? the dhw temp being too high is a historic issue isnt it , as you mentioned the servicing guy was attempting to reduce this 4 months ago ? he may not have picked up a potential problem with the diverter ,however that would not have a bearing on the issue with some rads getting very hot and one not working at all ,and others to various temps . do you want to try yourself to work on the blue rad ?

 

[chriselevate]

Ok so the DHW was a issue but after the answer was posted on here I was able to drop the DHW temperature by about 10 degrees and it's been fine since.

I've been running the CH tonight to try to get to the bottom of the issue and tonight I've managed to get the one marked BLUE to get REALLY hot. Problem is I can only get about 20% of the house on at once. Seems I can't figure out a pattern or a solution.

 

[terryplumb]

good ,what did you do to get it hot ,and status of all the other rads now ? and is dhw temp OK ?

 

[chriselevate]

So I managed to get it hot by running one radiator at a time and then getting to that one as the fifth radiator I managed to get it running hot. I still don't seem to be able to get all on though as it just seems to die down again. I'm just not sure what the best approach is to test it all.

The CH has been off for over an hour now and the DHW is still REALLY hot. Much hotter than it was set to.

 

[D_Hailsham]

Boiler starting readings are as follows:
flow temperature. 55
return temperature. 56
ionisation current. 0.0
fan speed 0

I would expect those numbers when the boiler was off. The flow and return temperatures are what the boiler has cooled to since last time it ran. Pump overrun will equalize the F and R temperatures.

After it's been on for 5 mins of CH the readings are as follows:
flow temperature. 71
return temperature. 69
ionisation current. 0.0
fan speed 0

The boiler has turned off.

After 10 minutes of CH:
flow temperature. 78
return temperature. 77
ionisation current. 0.0
fan speed 0

The boiler has turned off, again.

I notice that nF is NOT "between 13 and 50 (CH) or 67 (DHW)" as you mentioned. Is this the issue?

Update....

Switched on the rad marked in the diagram as RED and I got this...
t1, then a number, e.g 67. This is the flow temperature. 68
t2, then a number, e.g 44. This is the return temperature. 66
t3, then a number, e.g 55. This is the hot water temperature. --
t4, then --. This is the outside temperature, which requires an outside sensor. Don't worry about it. Yes it's --
Press + again and you will see FL, then, e.g 7.6. This is the ionisation current. Not important. 8.1
Press + again and you will see nF, the, e.g 22. This is the fan speed, which determines the boiler output, It will vary between 13 and 50 (CH) or 67 (DHW). 15

Monitor nF and see what it does. I suspect that it starts at about 15-20, then quickly drops to 13, and then to 0


Update...
Since it's been on, my DHW (out of the tap) has gone about 10-20 hotter. It's BOILING hot right now!

The diverter valve needs checking

 

[chriselevate]

Thanks. I think I've lost you there.

So you think I should have some rads switched on or off for my next tests? And you say I should "monitor nF and see what it does"? If you could let me know when you think I should check the readings I can have another go and let you know what the readings are. During all these tests I am making sure that the thermostat temp is well above the reading for the house so it continues to keep firing so I'm not ruining the tests with the boiler stopping part way through.

Yes, it sounds like the diverter valve needs checking like you say.

Thanks