Remeha 28c problem!

[Julieanneinspain]

We have a Remeha 28c that is showing a steady 8 on the LCD, (not E8 ) I cannot find any reference to that in the installation manual and Remeha tech will not help us any more because they say that they do not support installations outside the U.K (we are in Spain) despite this particular model being recommended by their salesman specifically because it will work with LPG and there was good technical support.
It was fitted 5 years ago by my brother (retired corgi registered) and checked and passed by Repsol (Spain's British Gas equivalent) for our 5 year certificate. It had a new PCB 1 year ago.
My brother has now put in a new actuator, new internal workings in the 3 way valve and new flow/return sensors, to no avail. It is still showing 8, the pump is running all the time and the boiler is trying to reset itself every 10 minutes or so. Consequently it is switched off until we need hot water.
I have phoned several central heating engineers over here but none will come to look at it because they have to be registered with the company to work on their boilers.
Any help at all would be greatly appreciated.
Julie-Anne.

 

[D_Hailsham]

Code 8 is a control stop and will appear if the measured flow temperature (t1) is higher than the flow temperature set (Tset flow). The boiler will start working again automatically once the flow temperature falls below the flow temperature set.

Code 5 is a control stop from 3 till 10 minutes and appears if the set flow temperature (t1) has already been reached and the heating demand still exists.

Code 9 is a shut down and appears if the maximum temperature rise is exceeded or if the dT between the supply and return temperature ≥ 45°C or a rate of rise in the flow temperature > 1°C/sec. And also at a boiler-start with no through flow or insufficient water. The boiler will try to restart after 10 minutes.

NB English versions of the Installation Manual incorrectly show these codes as d5, d8 and d9.

 

[Julieanneinspain]

Thanks for that D Hailsham, the problem is that the set flow temperature is 75 and the actual flow temp is 55.
(Return set temp is 55 and actual is 56).

Still in the dark!!!! But appreciate the help!
Julie-Anne.

 

[D_Hailsham]

Thanks for that D Hailsham, the problem is that the set flow temperature is 75 and the actual flow temp is 55.
(Return set temp is 55 and actual is 56).

You can't set the return temperature! It depends on the amount of heat removed from the water by the radiators and the flow rate.

If t1 is 55 and t2 is 56 no heat is being extracted from the boiler! Monitor the fan speed (that's nF), which relates to the boiler output. The lowest it will go to is 13 and max is 55. You need to monitor it from the time the boiler restarts until it goes out and code 8 appears. It will give a clue as to what is happening.

 

[D_Hailsham]

the problem is that the set flow temperature is 75 and the actual flow temp is 55. (Return set temp is 55 and actual is 56).

Just had a thought . Are the temperatures, 55 Flow, 56 Return, those which the display showed when the boiler there was a code 8? If so, that's to be expected.

When the code 8 conditions occur (t1 greater than set flow temp) the boiler turns off, but the pump continues to run circulating the water round the system. The rads will continue to give off some heat, so the flow temperature will drop until it is about the same as the return temp and the pump stops.

So we're back to your original question: why the code 8's?

1. Is this a new problem?
2. If so, when did it start?
3. Was any work carried out on boiler or system immediately prior to this?

Code 8 implies a lack of circulation.

Remeha contact info in Spain should help you find a Remeha authorized repairer.

 

[Boilerman2]

Or out of range Thermistors (replace them!)

 

[D_Hailsham]

Or out of range Thermistors (replace them!)

They have already been replaced - see first post; but have they been put in the correct position? ("When sensors have been taken out, be sure to replace them max. 40 mm underneath heat exchanger.")

When the PCB was replaced, were the correct values for dF and dU entered?

Has the error log been checked?

 

[Julieanneinspain]

Thank-you so much for thinking about this and trying to solve my problem!
D Hailsham and now Boilerman2.

To answer all your questions!
Firstly, the fan speed. From restart (ie, 1 pre-purge stage because I can not look at the fan speed whilst F2.2 and P1.0 are showing) is....
33-42-47-49-50-51-49-47-45-43-40-37-31-26-23-21
all this takes about 12 seconds and when I press R, 8 is there again.
But at this time the boiler is doing its start-up, so looking at the screen you would normally see 1, 2, 4, then it shows 8 instead of 7 then 0.

Whilst the boiler is showing code 8
t1 ranges between 51 and 57
t2 ranges between 54 and 60
t2 is always 1 or 2 higher than t1.

The set temp for flow is still 75 and has not been changed.

The only time the boiler does not show code 8 is on the start up, initially it shows F2.2 and P1.0 then it shows pre-purge 1, ignition stage 2, operating in DHW mode 4. Then directly to 8. There is no 7 pump run on, or 0 stand by. And for a split second as I unplug the boiler it shows 7.

The radiators have no heat at all, I can not get the heating to run.
I only have 3 radiators, they are all cast iron and on the ground floor.
I do not have a room stat just an internal digital time clock. I use the override button to switch heating on and off.

This is a new problem, it started in mid December. And there had been no work done to the boiler, at all, since 1 year before when the PCB was fitted. (Values for df and du are both 1.)

We think that the boiler started showing code 8 on the day that our electricity supplier fitted a new meter, (lights flickered a few times then went off for about 30 seconds) to supply cheaper electric between the hours of 23.00 and 13.00. That was when we noticed that the pump was running constantly. When we tried to put the heating on a few days later it wouldn't work but the hot water was not a problem.
We took the flow/return sensors off to check the resistance and when we put them back on (instead of having them dangling about) the boiler showed E0. We put new sensors on and pressed R, E0 disappeared but 8 still showed.

Error log shows one error as 0.

The sensors are positioned as near as they can be to the heat exchanger.

I now have found that t3 boiler temperature is showing -- instead of a figure. But if the boiler temperature sensor needs replacing I don't understand why it is not showing E0.
And since the return temp is higher than the flow temp why is the boiler not showing E2?
More questions, I'm really sorry!!!

Hope that answers everything, sorry its the size of a book!!!!
This thing is driving me to distraction!!!!

Again thank-you.
Julie-Anne.






[/u]

 

[D_Hailsham]

I have a horrible suspicion that the meter changer just cut the power without shutting down the boiler first and this has damaged the PCB.

As for your other information ...

fan speed. From restart (ie, 1 pre-purge stage because I can not look at the fan speed whilst F2.2 and P1.0 are showing) is....
33-42-47-49-50-51-49-47-45-43-40-37-31-26-23-21
all this takes about 12 seconds and when I press R, 8 is there again.
But at this time the boiler is doing its start-up, so looking at the screen you would normally see 1, 2, 4, then it shows 8 instead of 7 then 0.

No circulation, therefore faulty pump, faulty diverter, blockage. OR damaged PCB

Whilst the boiler is showing code 8
t1 ranges between 51 and 57
t2 ranges between 54 and 60
t2 is always 1 or 2 higher than t1.

And since the return temp is higher than the flow temp why is the boiler not showing E2?

Explained this earlier. When code 8 occurs, boiler goes out but pump still runs to cool the water down. T1 and T2 will approximately equalize.

The only time the boiler does not show code 8 is on the start up, initially it shows F2.2 and P1.0 then it shows pre-purge 1, ignition stage 2, operating in DHW mode 4. Then directly to 8.

mode 4 is hot water; were you calling for hot water? What happens if you ask for the heating, do you get a code 3?

I only have 3 radiators, they are all cast iron and on the ground floor.

So you won't need more than 10kw to heat them; the boiler output should be reduced using parameter 17.

I do not have a room stat

Fitting one would be a good idea

Values for df and du are both 1.

Correct values are on the data plate on the underside of the boiler.

I now have found that t3 boiler temperature is showing -- instead of a figure. But if the boiler temperature sensor needs replacing I don't understand why it is not showing E0.

This is a translation problem! The "boiler temperature" is the domestic hot water temperature. If you are not calling for hot water it will show --.

 

[Julieanneinspain]

Hi, thanks again. I will be forever in your debt!!!!!

Re, the PCB, this is what I have been thinking if only because it costs a fortune!!

We are sure that the pump is working, new diverter fitted. As for a blockage, it is definitely possible, brother will check that this week.

DHW code 4 always shows in the start up.
If I ask for heating the display stays showing 8, the override symbol shows on the clock along with 1 for on. The heating doesn't come on.

df and du values are both 1 on the data plate.

Appreciate the help but I think I will be ordering a new PCB!!!!

 

[D_Hailsham]

ldf and du values are both 1 on the data plate.

Appreciate the help but I think I will be ordering a new PCB!!!!

Check values of P3 (should be 1) and P30 (should be 0).

It might be worthwhile checking all parameters are as shown in the manual.

 

[Julieanneinspain]

P3 is 1, P30 is 0.

Have checked all the parameters, they are all as factory set except the adjustments for propane firing and df and du.

When I checked all the parameters, I got to df, press enter to confirm = 1, du press enter to confirm = 1. This then reset the values for propane firing back to natural gas. So I have to go back to P18 and 19 and change them again. Could this be anything to do with it?

I know I keep saying thanks but I really am grateful. You must be really bored by now D Hailsham!!!!

 

[D_Hailsham]

Can you post a legible pic of the data plate?

 

[Julieanneinspain]

Here it is, hope you can see it okay!

Julie-Anne

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Untitled

• Julieanneinspain
• 19 Jan 2014
• 1

 

[D_Hailsham]

When I checked all the parameters, I got to df, press enter to confirm = 1, du press enter to confirm = 1. This then reset the values for propane firing back to natural gas. So I have to go back to P18 and 19 and change them again. Could this be anything to do with it?

I haven't been able to check this, but I suspect that dF and dU are changed to 0 when parameters are altered from default values. Resetting dF and dU automatically resets all parameters. You should be able to confirm this by checking if either dF or dU has altered since you set P18 and P19 for propane use.

If this is the case but they were both showing 1, when you originally checked their values, it could be that the PCB had become confused; part of it thinking that you were using gas, the other part that you were using propane.

What is happening now? Do you still have the problem? Have you contacted Remeha Spain (link in my first post)?

As for the pic, I was curious where the dF and dU info were located as my Remeha boiler data plate does not show it.