Horstmann HRT3 wired incorrectly

[D_Hailsham]

I think there are 2 cables coming up from the programmer, one for HW and one for CH. The other I now think is from the boiler.

I'll wait for the pic.

I have noticed that the pump and the valve both whir away when the timer is on but the boiler is not fired up (this applies for both CH and HW). Is that how it is supposed to work?

No.

To my untrained mind I would expect the pump and valve only to come on if the thermostats also 'tells' the boiler to fire up.

Basically, that's correct. But the pump should carry on running for a few minutes after the boiler turns off to cool the heat exchanger down. It's the pump overrun. The pump has to be wired directly to the boiler (via the junction box) so the boiler can control the pump.

There is still the mystery of why the boiler sometimes but not always refuses to fire up even though the CH stat indicates temp is under the setting.

That's a wiring problem.

 

[n0v1ce1]

I'll wait for the pic.

Pics uploaded

 

[D_Hailsham]

Pics uploaded

Thanks. The programmer wiring diagram is the most useful.

What happens inside the "wiring box above the programmer"? Another diagram would help.

 

[n0v1ce1]

What happens inside the "wiring box above the programmer"? Another diagram would help.

I'll turn the power off tomorrow to have a look and take a picture. I may be able to marry up what is in there to the cable ends up in the airing cupboard.

 

[n0v1ce1]

[/quote]I'll turn the power off tomorrow to have a look and take a picture.[/quote]

Managed to see what is in the cable box above the programmer. Labels on some of the wires confuse me

View media item 90473

 

[D_Hailsham]

Assuming that the colours are correct in the cable box, I can see nothing wrong with the wiring.

So we need to look somewhere else for the cause of your problem. The first possibility is the blue motorized valve. Follow the sequence below and post what happens at each stage.

1. Turn CH and HW OFF at programmer
2. Set CH and HW stats to minimum
3. Turn HW ON at prog. (Boiler stays OFF)
4. Turn HW stat to Max (Boiler turns ON)
Pipe to cylinder gets hot
5. Turn HW stat to Min (Boiler turns OFF)
Pipe to cylinder cools
6. Turn CH ON at prog. (Boiler stays OFF)
7. Turn CH stat to Max (Boiler turns ON)
Pipe to rads gets hot
8. Turn HW stat to Max (Boiler stays ON)
Pipe to rads stays hot; pipe to cylinder gets hot
9. Turn HW OFF (Boiler stays ON)
Pipe to rads stays hot; pipe to cylinder cools down

 

[n0v1ce1]

Assuming that the colours are correct in the cable box, I can see nothing wrong with the wiring.

Thanks.

I had ticked off my diagram versus the circuit diagram supplied with the programmer that matched my installation, and I could not see anything that looked wrong either.

I will try that sequence of steps you suggested tomorrow.

 

[n0v1ce1]

[/quote]
I had ticked off my diagram versus the circuit diagram supplied with the programmer that matched my installation, and I could not see anything that looked wrong either.[/quote]

One of the (many) things that puzzles me is that in the off position for HW (according to the programmer booklet) power goes from Live to connection 1 in the programmer. Connection point one has a lead in it that takes power on to the cylinder stat and the valve (and then possibly onwards from them). It seems odd to me that power needs to go to the stat if the HW is off.

[/quote]I will try that sequence of steps you suggested tomorrow.[/quote]

I tries this at 10am today - the pipe from the valve to the cylinder stayed hot for ages, so cooling was not possible for me to easily detect. Once it is cool I will try the steps again.

 

[D_Hailsham]

One of the (many) things that puzzles me is that in the off position for HW (according to the programmer booklet) power goes from Live to connection 1 in the programmer. Connection point one has a lead in it that takes power on to the cylinder stat and the valve (and then possibly onwards from them). It seems odd to me that power needs to go to the stat if the HW is off.

This is necessary to make the valve work. Read Mid-position valve operation and fault finding for an explanation.

 

[n0v1ce1]

The first possibility is the blue motorized valve. Follow the sequence below and post what happens at each stage

1. Turn CH and HW OFF at programmer
done
2. Set CH and HW stats to minimum
done
3. Turn HW ON at prog.
done
(Boiler stays OFF)
yes
4. Turn HW stat to Max
done
(Boiler turns ON)
yes
Pipe to cylinder gets hot
yes
5. Turn HW stat to Min
done
(Boiler turns OFF)
yes
Pipe to cylinder cools
yes
6. Turn CH ON at prog.
done
(Boiler stays OFF)
yes
7. Turn CH stat to Max
done
(Boiler turns ON)
No - stopped here

It was about 6:30pm when I did this after both HW and CH had been left off all day. This is the issue that has often arisen, but as I said before there are times when the boiler does respond to the CH stat. If it follows past experience tonight, the boiler will fire up in about an hour.

 

[D_Hailsham]

Thanks for the test results,

I was hoping you would go right through to the end of the list, even if some steps 'failed'.

 

[n0v1ce1]

Thanks for the test results,

I was hoping you would go right through to the end of the list, even if some steps 'failed'.

ah! I will do it again then

 

[n0v1ce1]

As I expected it might, the boiler fired up about an hour after it was asked to do so (by the CH stat) at step 7 last night.

I went through the tests again this morning at about 08:30:

1. Turn CH and HW OFF at programmer - done
2. Set CH and HW stats to minimum - done
3. Turn HW ON at prog. (Boiler stays OFF) - boiler stayed off
4. Turn HW stat to Max (Boiler turns ON) - boiler turned on
Pipe to cylinder gets hot - pipe got hot
5. Turn HW stat to Min (Boiler turns OFF) - boiler turned off
Pipe to cylinder cools - yes it did
6. Turn CH ON at prog. (Boiler stays OFF) - yes, stayed off
7. Turn CH stat to Max (Boiler turns ON) - boiler did not turn on
Pipe to rads gets hot - no
8. Turn HW stat to Max (Boiler stays ON) - boiler turned on
Pipe to rads stays hot; pipe to cylinder gets hot - pipe to rads stayed cold, pipe to cylinder got hot
9. Turn HW OFF (Boiler stays ON) - boiler went off
Pipe to rads stays hot; pipe to cylinder cools down[/quote] - pipe to rads stayed cold, pipe to cylinder cooled down


I left the controls at the last settings above and the boiler fired up after about 30 mins wait. Rads now nice and warm. The pipe to the HW cylinder has also got very hot though even though the HW was still off at the programmer.

I am going to switch it all off and run through again later today.

 

[D_Hailsham]

1. Turn CH and HW OFF at programmer - done
2. Set CH and HW stats to minimum - done

The valve is in the default, unpowered, state. Port B (cylinder) is open

3. Turn HW ON at prog. (Boiler stays OFF) - boiler stayed off
4. Turn HW stat to Max (Boiler turns ON) - boiler turned on
Pipe to cylinder gets hot - pipe got hot
5. Turn HW stat to Min (Boiler turns OFF) - boiler turned off
Pipe to cylinder cools - yes it did

HW, on its own works. Step 5 should put 240V on the grey wire from the cylinder stat Sat terminal.

6. Turn CH ON at prog. (Boiler stays OFF) - yes, stayed off
7. Turn CH stat to Max (Boiler turns ON) - boiler did not turn on
Pipe to rads gets hot - no

The CH stat should apply 240V to the valve white wire. This, and the 240V on the grey wire should mean that the valve opens port A only (radiators).

Failure means:
1. Faulty valve (sticking or motor shot)
2. Voltage on grey but not on white

(Voltage on white but not grey would put valve in mid-position - CH and HW ON)

8. Turn HW stat to Max (Boiler stays ON) - boiler turned on
Pipe to rads stays hot; pipe to cylinder gets hot - pipe to rads stayed cold, pipe to cylinder got hot

It should have gone to mid-position (both HW and CH on0 but has reverted to the HW only position due to the above faults

9. Turn HW OFF (Boiler stays ON) - boiler went off
Pipe to rads stays hot; pipe to cylinder cools down - pipe to rads stayed cold, pipe to cylinder cooled down

HW OFF should have applied 240V to valve grey.

I left the controls at the last settings above and the boiler fired up after about 30 mins wait. Rads now nice and warm. The pipe to the HW cylinder has also got very hot though even though the HW was still off at the programmer.

So the valve had gone to mid position.

First thing to check is if the valve is sticking

Turn power off
Remove the actuator (Blue box)
Check that the spindle can be turned easily by hand (20 degrees only).
Replace actuator.
Move the lever at the end from Auto to Man. There should be resistance and the lever should return to Auto when released.

If that doesn't reveal any problems, more tests will be necessary. But that will be difficult due to the unorthodox wiring.

 

[n0v1ce1]

First thing to check is if the valve is sticking

Before seeing this I had repeated the sequence again and this time at step 7 the boiler did fire up, took about 2 minutes to do so.

Since then I have adjusted the CH stat a few times and the boiler has fired up every time.

I will try the steps again in full tomorrow and if it works properly maybe I've been lucky