Stovkis Hx econotrol panel - temp reading fault... No DHW.

[FrankE]

I was called to go to the clients to check the DHWS as the plumbers and electricians are from out of town and on their weekend off or at the client's other sites.
Being the weekend I can't get hold of Stovkis and their site won't let me register

The Stovkis Econotrol control panel temperature readout on the secondary was displaying >99deg C and the high temp alarm is latched even though the pipe is stone cold, leaving the unit interlocked out.

On cleaeing the alarm and manaully getting HW into the secondary tank so they don't have to shut down their business got the Hx running again, a process I had to repeat all day.

On booting up the valve and pumps run in sequence correctly and the temperature readout is accurate. This is short lived and the temp reading displays >99deg c again, the unit goes into fualt state and is interlocked out by the BMS.

Anyone had similar problem with these Hx controllers?
I think it's a problem with the PCB than the sensor since it does at times display the correct temerature.

Ayone know what type of temp sensor it is, thermistor? t/c? Pt100? so I can try out a third party sensor just to confirm iit's not the sensor until I get hold of Stovkis. It's not in a dywell so couldn't remove it.

 

[Agile]

Did you measure the sensor resistance ( cold ) ?

All boiler systems I can remember have always used NTCs. What did it look like?

On test you could have fitted a fixed resistor to see if the PCB was the cause of the false readings.

Did disconnecting the sensor give the same >99° reading? A real o/h situation would produce a low resistance on an NTC.

In an emergency, I have strapped an NTC on the outside, wrapped well on with 2.5 mm copper wire to transfer the heat and filled with silicone grease! Then turned down the set temp a bit to compensate for a smaller heat transfer. That can work for a few days until the correct part is obtained.

What are the premises used for?

Trade questions are better posted in the CC if you are gas registered.

Tony

 

[FrankE]

Thanks for the resonse wasn't sure whether to post in trade talk or here so picked here as more mech people who might know Plate Hxers frequent this forum.

Sensor was O/L (infinity) ohms cold. With sensor disconnected it didn't work at all and went straight to common temp alarm lockout. Miiliammeter was trashed by them and waiting repair so couldn't measure what it was drawing.

Had nothing in the way of components with me as was told it was fault with the bio-mass boiler and only took in with me what I could (and needed to) carry to faultfind on the boiler; Fluke, thermocouple probe and a few hand tools.

Didn't get the sensor out as the port started to leak water. As the tails of the sensor were heatshrinked as the sensor enters the wet port I thought removing it and getting it soaked was inviting more down time if I didn't have a spare.
If it is a drywell port which is leaking I would have expected erroneous readings from the outset. I didn't unscrew the drywell by mistake.

Checked the PID settings in case the unit was going into lockup due to instability. Various settings tried, no avail so set them back to default.

Passed it back to them anyway until they work out who is going to pay me for the work over the last few weeks since they laid me off. Will pack a bit more appropriately in case they have resolved payment and I get called out tomorrow. I'm signed off just now as had an arm op on Tuesday, working with one arm has made it bit awkward to do things.

It's food area so no HW is a showstopper otherwise I wouldn't have stayed.

 

[Agile]

Something is wrong with your measurement /interpretation!

If the sensor was o/c then connecting it or not would make no difference to the controller.

Quite apart from that I dont understand why you are going to do repairs when nobody has agreed to pay you.

I appreciate some people are very short of work but I hear of so many who go and repair boilers sometimes fitting expensive parts only to find the tenant is certainly not going to pay and does not know who the landlord is. Agents are not much better. You would have little chance of taking them to court just because the are an agent. To have any chance of getting paid you need an instruction in writing from a genuine legal entity.

Tony

 

[FrankE]

Something is wrong with your measurement /interpretation!

If the sensor was o/c then connecting it or not would make no difference to the controller.

Quite apart from that I dont understand why you are going to do repairs when nobody has agreed to pay you.

I appreciate some people are very short of work but I hear of so many who go and repair boilers sometimes fitting expensive parts only to find the tenant is certainly not going to pay and does not know who the landlord is. Agents are not much better. You would have little chance of taking them to court just because the are an agent. To have any chance of getting paid you need an instruction in writing from a genuine legal entity.

Tony

What's to measure wrong, a sensor with two leads, a fluke with two leads?

Baffles me too why the controller gives an initial reading with a sensor that reads o/c on an ohmeter.
Stokvis got back to me said "the resistance if the water was 99 deg would be around 138.5 ohms", making it a pt100. That should be about 108 at 20deg C

They'd a bit of a cheek to call me in after being told I'm signed off . Said one day I'd be finishing up that night. Later in the day the guy said "you won't be getting a job in the next couple of weeks will you, as we might need to call you in for a day here or there?"
Yeah like I'm going to sit in limbo waiting for their telephone call.

 

[Boilerman2]

Hi Frank its not a Hotel in Clacto on sdea by any chance?? only I'm feeling a bit De-ja-vu!! Stokvis = nightmare

 

[FrankE]

Hahaha, sounds just as grim

Stokvis called me this morning, actually pretty responsive and are Interlinking a sensor out overnight. They've arranged their local contractor to do a warranty replacement, so the site and the politics between the M and the E contractors are out of my hands thankfully. He didn't say anything of the controller initial reading seeming plausible.

The nightmare was that neither the M nor the E contractor wanted to take responsibility for getting the correct kit, putting amendements through, gettting datasheets. After 14 hour shifts (x7) I'd to come home hunt for datasheets on the web, e-mail suppliers for systems and panel mods. Just poor quality management If they'd undertaken design reviews we could have all gone home earlier with a modest profit.

Note to self: don't get involved in a project where the client doesn't want involvement in the project

 

[Agile]

I doubt that I will ever understand some of the things I read on these forums.

You seem to be saying 7 x 14 hour shifts when the legal limit is just 48 hours work per week.

And thats when you are "laid off" ?

Tony

 

[FrankE]

Yes. Legal working practices weren't the in thing on the site. Obviously those hours were when the project was ongoing, before I was laid off.

 

[Agile]

Its illegal for an employer to ask you to work that long.

Probably not relevant if you are a self employed contractor who sets his own hours. Unless he employs himself though.

Tony