Discuss Glowworm 18sx boiler + Danfoss Dual zone wireless system. Water not heating in the DIY Electrical Advice area at ElectriciansForums.net

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aidanodr

Hi Guys,

We have a Glowworm 18sx boiler. We have 2 zones - one for heating, the other for hot water. All controlled by Danfoss wall panel, thermostats & actuators ( these near cistern ). All this installed end of 2011.

The heating zone has thermostat in hall while the water thermostat is near the cistern.

Recently the system has not been heating water, the boiler does not fire up. To narrow down the possibilities I tried the heating zone - the boiler fired up straight away.

So from that I concluded it was not the boiler which had only been serviced two weeks ago.

I then went to the actuator in by the cistern for the Heated water zone. This is a Danfoss HPA2 actuator. On the side of these is a lever that flicks from AUTO to MANUAL. I flicked it to manual which bypasses thermostat etc ( I think ) and the boiler fired up - when left like this it heats water fine.

I unscrewed the HPA2 off its bottom plate to expose the valve on the pipe - see if anything up there, that turns fine & freely. Put the HPA2 back on with the lever set back to AUTO.

Low and behold the heated water zone later on came on by itself at the time it was supposed to so back to normal.

This worked for a few days BUT now I am back to square one. To heat the water i have to flick the HPA2 lever to manual and then back to auto after a while when water is heated enough.

Im trying to figure out what component has gone wrong here.

Is it the HPA2 packing up? The motor inside it? Are these HPA2 actuators a good product? Do they give trouble?

Is it the valve under the HPA2 that is sticking?

Is it the Thermostat?

Any thoughts / fixes?

The system we have is wireless involving a Danfoss Dual zone wall panel ( heating programming left, water programming right ). A Danfoss CET-B RF Cylinder Thermostat, a Danfoss RX1 Room Thermostat, a RX-2C Wireless Reciever Two Channel, 2 x Danfoss HPA2 Actuators ( one for each zone ).
 
Hi Guys,

We have a Glowworm 18sx boiler. We have 2 zones - one for heating, the other for hot water. All controlled by Danfoss wall panel, thermostats & actuators ( these near cistern ). All this installed end of 2011.

The heating zone has thermostat in hall while the water thermostat is near the cistern.

Recently the system has not been heating water, the boiler does not fire up. To narrow down the possibilities I tried the heating zone - the boiler fired up straight away.

So from that I concluded it was not the boiler which had only been serviced two weeks ago.

I then went to the actuator in by the cistern for the Heated water zone. This is a Danfoss HPA2 actuator. On the side of these is a lever that flicks from AUTO to MANUAL. I flicked it to manual which bypasses thermostat etc ( I think ) and the boiler fired up - when left like this it heats water fine.

I unscrewed the HPA2 off its bottom plate to expose the valve on the pipe - see if anything up there, that turns fine & freely. Put the HPA2 back on with the lever set back to AUTO.

Low and behold the heated water zone later on came on by itself at the time it was supposed to so back to normal.

This worked for a few days BUT now I am back to square one. To heat the water i have to flick the HPA2 lever to manual and then back to auto after a while when water is heated enough.

Im trying to figure out what component has gone wrong here.

Is it the HPA2 packing up? The motor inside it? Are these HPA2 actuators a good product? Do they give trouble?

Is it the valve under the HPA2 that is sticking?

Is it the Thermostat?

Any thoughts / fixes?

The system we have is wireless involving a Danfoss Dual zone wall panel ( heating programming left, water programming right ). A Danfoss CET-B RF Cylinder Thermostat, a Danfoss RX1 Room Thermostat, a RX-2C Wireless Reciever Two Channel, 2 x Danfoss HPA2 Actuators ( one for each zone ).

Hi, welcome to the forum. Have you checked to see if the RX2C and wireless cylinder thermostat are still talking to each other? Dead batteries or loss of signal.
 
Last edited:
Hiya Leesparkykent,

Thanks for reply.

Their is no low battery indicator flashing on the thermostat. I wonder is that reliable? Even if that is not there should I replace battery anyway? It has been working away on original battery since late 2011.

There is the little flame symbol on the thermostat I/F though.

It seems to communicate with the RX2C via Learn button, but I do notice the red light for that zone is constantly on, on the RX2C. The thermostat is set at 63 degrees ( as instructed to prevent pathogens in cistern ). BUT the thermostat reading is now down to 30 degrees.

There is also a block sensor thing up against the cistern & tied there. A wire goes from this into the thermostat. I assume that reads the current temperature of the cistern and has nothing to do with this problem?

Aidan




 
Last edited by a moderator:
Hiya Leesparkykent,

Thanks for reply.

Their is no low battery indicator on the thermostat. I wonder is that reliable? Even if that is not there should I replace battery anyway? It has been working away on original battery since late 2011.

It seems to communicate with the RX2C via Learn button, but I do notice the red light for that zone is constantly on, on the RX2C. The thermostat is set at 63 degrees ( as instructed to prevent pathogens in cistern ). BUT the thermostat reading is now down to 30 degrees.

There is also a block sensor thing up against the cistern & tied there. A wire goes from this into the thermostat. I assume that reads the current temperature of the cistern and has nothing to do with this problem?

Aidan





Are you getting the green light flash up when you press prog and the appropriate channel button simultaneously whilst it's in learn mode?
 
If you are confident every thing is paired correctly the next step would be to check for voltage in sequence of the switching.
For this you would need the correct test equipment and be competent to carry out the job in hand. You may require the assistance of an electrician to do this for you.
 
You asked "Are you getting the green light flash up when you press prog and the appropriate channel button simultaneously whilst it's in learn mode?"

Short answer - YES

Their are two red lights on the RX2C. One ( was ) ON ( Water ), the other OFF ( Heat ). The latter is off as we are not using the heating at the moment + I have the wall thermostat for heat way down in temp, so no demand.

The red light that is on is the channel for the heat water. It WAS permanently on.

I pressed LEARN on the Thermostat .. red light goes off on RX2C. But I think you need to let the learn process happen for 5 minutes. I did that. Then one presses the appropriate zone light button plus PROG button on the left simultaneously. I did that also.

Then nothing, no red lights, no flickering green lights on the RX2C after Learn.
 
Last edited by a moderator:
No the RX2C doesn't need batteries as it's hard wired. I'm not overly familiar with Danfoss controls but with a voltage tester you would be able to see whats switching and what isn't.

http://heating.danfoss.co.uk/PCMPDF/25322v07.pdf

follow the instructions in the link to pair the device you should get a green flashing light on the RX2C to let you know it has paired.
 
Last edited:
OK, thanks LPK,

Will have to get in a sparks id say.

Now both red lights are on, on the RX2C, even though wall thermostat is set down at 9 deg and no demand ..
 
Last edited by a moderator:
I have pushed the HPA2 actuator lever over to manual to bypass .. now boiler on heating water. But have to remember to pop back to auto in about an hour :D ( Bypasses wall controls by boiler )

I suppose if the HPA2 for the heating zone is working it probably means the RX2C is OK. So it must be either the Thermostat for the water / cistern OR the HPA2 for the heat water zone that is borked. My money is on the HPA2 - that auto to manual lever needs a good push to get it over and clicked into manual mode.
 
Last edited by a moderator:
OK, thanks LPK,

Will have to get in a sparks id say.

Now both red lights are on, on the RX2C, even though wall thermostat is set down at 9 deg and no demand ..

Switch it off, remove the batteries from thermostats, leave it a few minutes, turn back on, replace batteries in thermostats and repeat commissioning process in the instructions. If it doesn't work you will have to get a sparks in.
 
No Difference ... something else gone dodgy ..

Sparks time .. thats OK, just wanted to make sure nothing simple first before calling in the big guns :D

Thanks for your help ..
 

Reply to Glowworm 18sx boiler + Danfoss Dual zone wireless system. Water not heating in the DIY Electrical Advice area at ElectriciansForums.net

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