Heating electric controls running hot/ burning, oil heating

[speedystu]

Hi all Happy Christmas to you and yours.

I need some expert advice

I made the temporary leap to a off grid Mobile home a few months ago while I build my house.

All works ok, generator during the day and batteries and a 1 to 2 kw 220v inverter at night.

However, there is a slight problem, I am using an oil boiler out side for heat. Something is burning/melting a hole in the control panel? It's going on for months, don't think it's hot all the time bit can't be sure. Is the wiring wrong or what can be causing this? It's already killed one control panel. A worrying site to me. Possible problem s would be helpful. A newly qualified electrician did this install. Thank you all.

 

[timhoward]

It looks as though that controller is wired to control hot water too, how is the water heated in this mobile home?
If that's the 2nd controller this has happened to, then it points to either the load(s) it's switching being faulty or the load being higher than the controller is rated to switch.
What is the rated power of the oil boiler? And to repeat is the oil boiler heating hot water too or is that a different system?

 

[speedystu]

It looks as though that controller is wired to control hot water too, how is the water heated in this mobile home?
If that's the 2nd controller this has happened to, then it points to either the load(s) it's switching being faulty or the load being higher than the controller is rated to switch.
What is the rated power of the oil boiler? And to repeat is the oil boiler heating hot water too or is that a different system?

Thank you for replying, Well spotted, there's two motorised switches, see pic, do you mean the power rating for the oil boiler? It heats a water cylinder, not electric cylinder.

 

[speedystu]

It looks as though that controller is wired to control hot water too, how is the water heated in this mobile home?
If that's the 2nd controller this has happened to, then it points to either the load(s) it's switching being faulty or the load being higher than the controller is rated to switch.
What is the rated power of the oil boiler? And to repeat is the oil boiler heating hot water too or is that a different system?

 

[Avo Mk8]

It could be overloading the relays/contacts/pcb tracks, or it could be that the power supply in the controller doesn't like the waveform from your inverters (or generator), assuming that's what it is running from?
I'd be inclined to take the cover off the controller, and see what's overheating - that might give a clue to what's going on.
A photo of what's getting hot might help

 

[speedystu]

It could be overloading the relays/contacts/pcb tracks, or it could be that the power supply in the controller doesn't like the waveform from your inverters (or generator), assuming that's what it is running from?
I'd be inclined to take the cover off the controller, and see what's overheating - that might give a clue to what's going on.
A photo of what's getting hot might help

Cover off, board looks intact. Will try a close up.

 

[speedystu]

View attachment 93477
Cover off, board looks intact. Will try a close up.

 

[speedystu]

View attachment 93479

Looks heated/burnt under screw

 

[timhoward]

That’s a good shout from @Avo Mk8 - are the inverters modified sine wave or pure sine wave.
It does look as if that resistor is cooking.

 

[speedystu]

Wha

That’s a good shout from @Avo Mk8 - are the inverters modified sine wave or pure sine wave.
It does look as if that resistor is cooking.

That’s a good shout from @Avo Mk8 - are the inverters modified sine wave or pure sine wave.
It does look as if that resistor is cooking.

I can't tell, when I was looking for an invertor I struggled to find one at all that wasn't 1000s , which sine wave is preferred? I do need to change the inverter, its not powerful enough. If I get another what type of sine wave do I need for this Heating application?

 

[speedystu]

https://cpc.farnell.com/unbranded/swinv1000/inverter-1000w-with-twin-usb/dp/CP06256?CMP=i-ddd7-00001003

No mention on the sales site, I bought them here.

 

[speedystu]

That’s a good shout from @Avo Mk8 - are the inverters modified sine wave or pure sine wave.
It does look as if that resistor is cooking.

Cooked the underside of the cover, what is this problem, thanks guys, off-grid is no joke

 

[Avo Mk8]

Looks heated/burnt under screw

I think it's those two resistors overheating. The pcb colour is probably as a result.
We seem to be in the mains/psu area judging from that big capacitor.
Without a circuit diagram difficult to know what's happening - no doubt Lucien would have some words of wisdom.

I stick with my "it doesn't like your generator/inverter supply" theory.

You could see if it only get hot at night (inverter) or only gets hot daytime (generator)?

What you need is one or two good old fashioned synchronous motor driven time clocks instead

To be serious - synchronous motor timers are still available, eg

https://www.NoLinkingToThis/p/horstmann-425-tiara-programmer/18470

But accuracy of clock dependent on frequency of your inverter/generator. May not be a problem

 

[timhoward]

Wha



I can't tell, when I was looking for an invertor I struggled to find one at all that wasn't 1000s , which sine wave is preferred? I do need to change the inverter, its not powerful enough. If I get another what type of sine wave do I need for this Heating application?

Modified Sine Wave inverters are cheaper but the waveform is different to that of ‘normal’ mains electricity. There are known problems with MSW inverters causing some power supplies to overheat.
You will pay a lot more for a pure sine wave inverter but that is likely the solution.
Alternatively finding a 2nd hand Sangamo mechanical time switch is potentially also a viable solution.
E.g.

SANGAMO S347.1.21 Time Switch Main Switch 80A | eBay

Find many great new & used options and get the best deals for SANGAMO S347.1.21 Time Switch Main Switch 80A at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

 

[Avo Mk8]

Cooked the underside of the cover, what is this problem, thanks guys, off-grid is no joke

The information on your specific SWINV1000 inverter includes the following:

*Important Information: *

Our modified sine wave inverters are suitable for general requirement for use inside vehicles, boats, caravans and boats. They are suitable for:

• powering laptops • phone chargers • tablets & games consoles • heater element devices such as kettles • vacuum cleaners • water pumps • Lower wattage home appliances – toaster, kettles, irons, electric hobs.
• Lighting (non ballast) • Many power tools

Our modified sine wave inverters are not suitable / recommended for:

• Solar installations • Medical equipment, such as CPAP machines with humidifiers • Power tools running on AC motor and variable speed control and cordless tool battery chargers. • Some Newer TV’s – refer to manufacturer guide. • Items with digital clocks and electric timers including washing machines and bread makers. • Devices that use thyristors like laser printers and photocopiers • Fluorescent lights • Audio Equipment, satellite systems and video equipment • High power items which use an AC motor such as larger fridges, microwaves and compressors.

 

[speedystu]

I think it's those two resistors overheating. The pcb colour is probably as a result.
We seem to be in the mains/psu area judging from that big capacitor.
Without a circuit diagram difficult to know what's happening - no doubt Lucien would have some words of wisdom.

I stick with my "it doesn't like your generator/inverter supply" theory.

You could see if it only get hot at night (inverter) or only gets hot daytime (generator)?

What you need is one or two good old fashioned synchronous motor driven time clocks instead

To be serious - synchronous motor timers are still available, eg

https://www.NoLinkingToThis/p/horstmann-425-tiara-programmer/18470

But accuracy of clock dependent on frequency of your inverter/generator. May not be a problem

Thank you and everyone else, just have the heat on now off the generator, no heat off it, I need to change the inverter but it'll probably be the same. Will the mechanical one still work with the hot water the accuracy of clock is not so much of an issue, hard to have constant power, the change over switch is manually operated by my wife and I. Tend to have the heat on a lot. The plumber did a great job, everyone here helped me understand my power plan and I've adapted accordingly, ps the washer and drier is at my parents house

 

[brianmoooore]

Fortunately, your plumber has connected up the system as a 'S' plan, rather than a 'Y' plan, so all you need is two simple time switches, one for the water, and one for the heating.
These could even be cheap plug in timers, since this is only a temporary installation. The current switching requirements are very low, so there shouldn't be a problem with the switch contacts overheating.

 

[speedystu]

Fortunately, your plumber has connected up the system as a 'S' plan, rather than a 'Y' plan, so all you need is two simple time switches, one for the water, and one for the heating.
These could even be cheap plug in timers, since this is only a temporary installation. The current switching requirements are very low, so there shouldn't be a problem with the switch contacts overheating.

Hi thanks, so you mean the electric valve switches are not needed? Or just the Electronic control box needs to go, the easiest for me would be to get the mechanical version as all the wiring is done already ? Just tested over 4 hours on generator, no heat on panel, that must mean the problem is the Invertor output as correctly identified by you smart folks is the culprit.

 

[brianmoooore]

The two electric valves have to stay. One controls the flow through the cylinder and the other the flow through the radiators. Both have a switch that controls the boiler and pump.
The valves have a manual lever on them, which you push across and drop into a notch. These can be used to operate the heating and hot water with no switches at all.
That resistor in the controller is designed to run warm (it's a large version of a resistor, and is situated by a vent in the case), and its likely purpose is to drop the 230V supply to 5 or 12V for the electronics.
I don't know exactly why it doesn't like your invertor, but the invertor seems to be the problem.

 

[speedystu]

The two electric valves have to stay. One controls the flow through the cylinder and the other the flow through the radiators. Both have a switch that controls the boiler and pump.
The valves have a manual lever on them, which you push across and drop into a notch. These can be used to operate the heating and hot water with no switches at all.
That resistor in the controller is designed to run warm (it's a large version of a resistor, and is situated by a vent in the case), and its likely purpose is to drop the 230V supply to 5 or 12V for the electronics.
I don't know exactly why it doesn't like your invertor, but the invertor seems to be the prob

The two electric valves have to stay. One controls the flow through the cylinder and the other the flow through the radiators. Both have a switch that controls the boiler and pump.
The valves have a manual lever on them, which you push across and drop into a notch. These can be used to operate the heating and hot water with no switches at all.
That resistor in the controller is designed to run warm (it's a large version of a resistor, and is situated by a vent in the case), and its likely purpose is to drop the 230V supply to 5 or 12V for the electronics.
I don't know exactly why it doesn't like your invertor, but the invertor seems to be the problem.

Would the mechanical clock/control s solve the problem?

I understand what you are saying about manual operation, I saw that switch myself but how would we turn on the heating with the digital panel gone, just use the main power switch?

Thank you very much !!

 

[Avo Mk8]

Would the mechanical clock/control s solve the problem?

A mechanical 2 channel timer like the Screw*** one I suggested earlier (there are other types available) would I think do the job. I don't have personal experience of running a synchronous motor from a modified sine wave inverter, but the Crouzet type clock motors are usually pretty robust (other than in 3 port valves - which you don't have!)

Edit - I do see mention on a forum re off-grid users that mechanical timers in older (eg) washing machines are fine with MSW inverters.

If you normally have regular water and heating on/off periods every day of the week it would be a practical substitute. You might need to change the wiring onto the bracket that comes with a new timer.

But you did mention you would like a more powerful inverter, so a replacement 'pure sinewave' version might also solve the problem using your current timer, which still seems to be working!

 

[timhoward]

I understand what you are saying about manual operation, I saw that switch myself but how would we turn on the heating with the digital panel gone, just use the main power switch?

I don't want to confuse the issue too much, as answering this leads you away from the best solution - changing the inverter or using less fussy time switch(es).
The answer - Inside the two port valve is a switch arranged so when the valve opens the boiler fires. The system is conventionally arranged so the time controller and room stat (if any) control whether the valve opens or not, and if the valve is open the boiler will fire.
So as long as it's been wired the conventional way then turning the time switch off, and moving and hooking the lever on the heating valve should result in the boiler firing, the pump starting, and the heating coming on. (In this mode there is usually no thermostatic control of it, it will stay on until manually turned off again.)
It is not a given it's been wired like this though.
In any case, whether this works or not, it's best to focus on solving the primary issues.

 

[Avo Mk8]

I don't want to confuse the issue too much, as answering this leads you away from the best solution - changing the inverter or using less fussy time switch(es).
The answer - Inside the two port valve is a switch arranged so when the valve opens the boiler fires. The system is conventionally arranged so the time controller and room stat (if any) control whether the valve opens or not, and if the valve is open the boiler will fire.
So as long as it's been wired the conventional way then turning the time switch off, and moving and hooking the lever on the heating valve should result in the boiler firing, the pump starting, and the heating coming on. (In this mode there is usually no thermostatic control of it, it will stay on until manually turned off again.)
It is not a given it's been wired like this though.
In any case, whether this works or not, it's best to focus on solving the primary issues.

Hi Tim, forgive me, I'm not an authority on this, but I was under the impression that latching a 2 port lever does not operate the microswitch, at least not on Honeywell valves. Plumbers maintain that the lever is for draining the system, not a substitute way of fully opening the valve. It may be different for different makes of valve, but I'm just suggesting there's a possibility this might not work! I apologise in advance if I'm wrong

 

[timhoward]

Hi Tim, forgive me, I'm not an authority on this, but I was under the impression that latching a 2 port lever does not operate the microswitch, at least not on Honeywell valves. Plumbers maintain that the lever is for draining the system, not a substitute way of fully opening the valve. It may be different for different makes of valve, but I'm just suggesting there's a possibility this might not work! I apologise in advance if I'm wrong

You are right. When latched the lever stops short of the micro switch. I forgot that.
All the more reason to fix this properly!

 

[speedystu]

A mechanical 2 channel timer like the Screw*** one I suggested earlier (there are other types available) would I think do the job. I don't have personal experience of running a synchronous motor from a modified sine wave inverter, but the Crouzet type clock motors are usually pretty robust (other than in 3 port valves - which you don't have!)

Edit - I do see mention on a forum re off-grid users that mechanical timers in older (eg) washing machines are fine with MSW inverters.

If you normally have regular water and heating on/off periods every day of the week it would be a practical substitute. You might need to change the wiring onto the bracket that comes with a new timer.

But you did mention you would like a more powerful inverter, so a replacement 'pure sinewave' version might also solve the problem using your current timer, which still seems to be working!

Thank you very much, I studied some electronics years ago, never knew I'd be this worried about sine waves thanks very much you and everyone who contributed to this answer .

 

[brianmoooore]

The Danfoss 2 port valve, which I have installed hundreds of, over the years, definitely operate the micro switch when the manual lever is engaged.