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reynard883
29-09-2016, 01:02 PM
Hi
Has anyone else had the problem of a Danfoss solenoid coil overheating and sticking to the stem?

If so any tips on best methods to remove them?

Tycho
29-09-2016, 04:30 PM
I've had that problem on a few occasions, usually with very old solenoids, where water has gotten between the coil and the stem.

I have found that the best way to remove them is to use a pipe wrench on the coil to rotate it back and forth while applying gentle pressure from below with a large flat head screwdriver.

it might take 5-10 minutes to work it all the way to the top, but the clue is to not use too much angular force so you don't break the thin steel on the stem.


Hope this helps :)

reynard883
29-09-2016, 04:38 PM
I've had that problem on a few occasions, usually with very old solenoids, where water has gotten between the coil and the stem.

I have found that the best way to remove them is to use a pipe wrench on the coil to rotate it back and forth while applying gentle pressure from below with a large flat head screwdriver.

it might take 5-10 minutes to work it all the way to the top, but the clue is to not use too much angular force so you don't break the thin steel on the stem.


Hope this helps :)

Thank you for the advice. I resorted to being very careful will a junior hacksaw cutting away at the coil until I exposed the small ridge area on the stem. I found that the plastic of the coil assembly melted into this area an thus keying itself onto the stem.

I had to be very careful not apply too much stress onto the body as the pipework in this area is very small and behind this is a 360kg flooded system with no means of isolation!

Grizzly
29-09-2016, 04:46 PM
Well Done.
Caution is always the best policy!
And welcome to the forum.
Grizzly

Tycho
29-09-2016, 08:21 PM
Thank you for the advice. I resorted to being very careful will a junior hacksaw cutting away at the coil until I exposed the small ridge area on the stem. I found that the plastic of the coil assembly melted into this area an thus keying itself onto the stem.

I had to be very careful not apply too much stress onto the body as the pipework in this area is very small and behind this is a 360kg flooded system with no means of isolation!

that sounds like a lot of patient work :D

Like Grizzly said "Caution is always the best policy!"

I hope you meant the ridge at the top, and not the ridge at the bottom, had it been a Normaly open valve :)

But best of all, you used your brains, identified the issue, used common sense and fixed the problem :)

Welcome to RE, and I hope we'll see you again :)

RANGER1
29-09-2016, 08:49 PM
Reynard,
As Tycho suggested moisture can cause burn out of coil.
Make sure "0" ring on bottom of armature tube & secure coil on properly to seal everything.
Otherwise solenoid could be faulty for some reason not lifting plunger, so overheating.

hvac01453
30-09-2016, 04:06 AM
Reynard,
As Tycho suggested moisture can cause burn out of coil.
Make sure "0" ring on bottom of armature tube & secure coil on properly to seal everything.
Otherwise solenoid could be faulty for some reason not lifting plunger, so overheating.

I bumped into one of these Danfoss SOV's today, covered in blue plastic. How the hell do you take the power head off? Sporlan has a small cap that pops off the top, but this one doesn't seem to have a way to release. It spins easily, only 3years old. Any insight?

RANGER1
30-09-2016, 04:38 AM
I bumped into one of these Danfoss SOV's today, covered in blue plastic. How the hell do you take the power head off? Sporlan has a small cap that pops off the top, but this one doesn't seem to have a way to release. It spins easily, only 3years old. Any insight?

http://products.danfoss.com/productrange/refrigeration/solenoid-valves/coils-solenoid-valves/

Id like this use lever like screwdriver to lever it directly upwards.
Has a strong clip to hold in place.

mbc
30-09-2016, 05:47 PM
14352

Hi
Ranger

as you know we have these type of coil
mbc

Glenn Moore
01-10-2016, 01:16 AM
All the previous advice on these coils is helpful , but the cause of coil failures is often due to simple errors in coil selection or fitting. Many manufacturers for logistic reasons often only stock a couple of coil voltages but with dual frequency design. They use this coil for both UK and European systems. If we look at typical UK voltage and frequency most voltages around the UK are approx 240 vo lt 50 hz. But often to reduce their coil stocks they fit a "universal one size fits all coil" ie the 230 volt dual frequency coil 50/60 hz . Often on large sites they have there own electrical sub stations where the single phase voltage I have personally measured has been as high as 256 volts 50hz.
If the 230 volt 50/60hz coil is fitted on a system that actually has this higher voltage supplied then the coil core temperature will climb to a point where the coil encapsulation starts to create small hair line cracks which moisture can enter into the coil winding.
As the coil energises and de- energises the coil expands and contracts and will draw moisture into itself as it breaths.
So we as the service engineers must fit the right coil for the actual voltage / frequency of the system. Manufacturers always keep their stock inventory as small as possible to keep costs low but often this causes coil failures due to the coil being used outside its design ratings.
The O ring seal at the bottom of the tube is the most important part as if this is not fitted or is damaged moisture can be drawn up inside the coil, the moisture during energisation will boil and melt the encapsulation and then a melted portion of the encapsulation "normally on the front side" puuks out like a small volcano. If you look up into the hole where the armature goes , you can see the exposed flux sleeves if moisture has got into the coil then often these flux sleeves go rusty. When the coil overheats due to over voltage / dual frequency coil/ fitted to very hot discharge valve,etc this often causes the coils waterproofing fluid to weep from the flux sleeve area this is often a white substance. When the plastic encapsulation melts into the armature hole , this normally occurs when the coil is off the valve while still energised.
Always fit the correct coil for the valve type (wattage size) and the correct voltage and frequency as measured on the site
Never just line size a solenoid valve

Grizzly
01-10-2016, 10:40 AM
What a brilliant reply Glenn.
Some really useful points
Thank you!
May I add that the whole UK Supply network has never ben more unstable.
With quite large variations of voltage being experienced at times.
Which make your observations all the more relevant.
Grizzly

monkey spanners
01-10-2016, 03:50 PM
Heres one I found blown a while back,

https://www.youtube.com/watch?v=0zdACXNEfCg