Author Topic: fridge thermostat replacement (Read 21650 times)

Odysseus · « **on:** September 29 2013, 10:32 »

This year I had to replace mine so took photos.

The first photo is the thermostat, its made by dunfoss and cost £14 off Bavaria agent Clipper marine.

The second photo is the position of the unit.

You can use the existing cables so no re running of cable.

Take cover off plate and under it is another plate with condenser onit, unclip fan cable, undo 4 screws 2 at top 2 at bottom. The condenser plate can then be moved away from bulkhead to remove old thermostat unit.

Thermostat can then be taken out of location and replaced, the coil of pipe should be put at back of condenser plate see photo or check yours before removal.

Replace in reverse.

Hope this helps.

Odysseus

Baltic · « **Reply #1 on:** October 11 2013, 07:24 »

We are not 100% satisfied with original thermostat.

Sometimes box temperature was +7 and another time -2 C.
Depending how much ice there is inside the evaporator.
My opinion. Bad engineering.
(Danfos DB35F + VD-15)

We replaced original thermostat with electronic model.
Temperature sensor installed just on the wall of box. Not inside the evaporator.

http://www.conrad.com/ce/en/product/190768/H-Tronic-temperature-switch-with-front-panel/?ref=detview1&rt=detview1&rb=2

Odysseus · « **Reply #2 on:** October 11 2013, 09:53 »

That sounds a good idea, my hysteresis was is the same, have you got a photo of the installation and I take it that only 2 wires are used.

Odysseus

Baltic · « **Reply #3 on:** October 11 2013, 16:08 »

Hi

Relay of Electronic thermostat is connected directly to the compressor C and T.
(Relay and resistor, R1 )
Old thermostat wiring to the evaporator is currently unused.

Attached Danfos BD35F specs.

Moodymike · « **Reply #4 on:** October 11 2013, 17:05 »

Can you give a description of how you attached the sensor and exact location? Is the supplier Europe based and does price include sensor?

Baltic · « **Reply #5 on:** October 11 2013, 18:03 »

Hi

Sensor location.
About 10-15 cm from top of box.
Another side the box where evaporator is located.

Original thermostat will measure temperature of evaporator. And result will be something between freeze and too warm.
New thermostat is measuring temperature of box.
More stable temp and less ice inside the evaporator.
Ice is problem. It will block air flow and evaporator is not working properly.

Supplier Htornic
Amazingly.. German made. (Not China)
http://www.h-tronic.de/
Price is including sensor.

Any Electronic thermostat which support cooling is possible to use.
Another model for example. Made by vellema
http://www.conrad.com/ce/en/product/190655/Velleman-VM148-thermostat-module/?ref=detview1&rt=detview1&rb=2

I chooce Htronic.
Better boxed sensor and operating voltage up to 15v.

Nigel · « **Reply #6 on:** April 05 2015, 10:44 »

As this thread has been linked to recently, I thought i would mention that I'm planning on using a 12V Digital Temperature Controller. Thermostat and display for under £10.

Moodymike · « **Reply #7 on:** April 05 2015, 11:23 »

How are you planning to install sensor and wireing circuit?

paulemeier1 · « **Reply #8 on:** April 05 2015, 19:04 »

Hello Baltic, you are from germany? It will be much esasyer to comunicaze. I am very interested to more about your freeze thermostat.
I own a 37 CR build 2006 lying in Grossenbrode.
Kind regards

Baltic · « **Reply #9 on:** April 07 2015, 15:09 »

Hi

"Hello Baltic, you are from germany? "

Sorry. No.
And very limited skills of German.

Kairos · « **Reply #10 on:** July 07 2015, 17:58 »

Quote from: Nigel on April 05 2015, 10:44

As this thread has been linked to recently, I thought i would mention that I'm planning on using a 12V Digital Temperature Controller. Thermostat and display for under £10.

Thx a lot of this!
I Just purchased the item below to replace the old thermostat.
I will place it close to compressor out of eyes, so the illuminating digits does not disturb... but easily checked if needed.

http://www.ebay.co.uk/itm/50-110-C-Digital-Heat-Cool-Temp-Thermostat-Temperature-Control-Switch-DC12V-New/351399680014?_trksid=p2054897.c100204.m3164&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140407115239%26meid%3D0a34b594db84488d9481d1788dd09ac9%26pid%3D100204%26rk%3D1%26rkt%3D30%26mehot%3Dpp%26sd%3D321621246653

ZhuHai · « **Reply #11 on:** July 11 2015, 03:37 »

I replaced the genuine thermostat by an electronic one found on amazon for less than 10 pounds http://amzn.to/1dV35w2

It is installed close to the compressor so I can control the temperature without opening the fridge.

Baltic · « **Reply #12 on:** July 11 2015, 07:39 »

Please note.

When acquiring thermostats.

I am not engineer
But there in boat. Operation voltage can be typically between 11.5 and 14.5 V.
In some cases.
If thermostat is build to work only with 12 V.
I might be. Switching temperature will change if operating voltage is changing.

As well if thermostat is build by using 12 V relay. It might start to work undesirable way if voltage drop under 12V.

Better choose thermostat which is build to operate multi voltage area. Like 10 to 15 V.

MarkTheBike · « **Reply #13 on:** July 11 2015, 10:17 »

Quote from: ZhuHai on July 11 2015, 03:37

I replaced the genuine thermostat by an electronic one found on amazon for less than 10 pounds

Hi ZhuHai

That's a good idea but Baltic has a valid point about the voltage fluctuation. I guess no-one would still have their fridge switched on if their batteries are discharged down to less than 12v but would it not be possible to add a small circuit that limits anything over to the required 12v +/-10%?

Impavidus · « **Reply #14 on:** July 11 2015, 18:01 »

If it is any help.... Our fridge compressor is also fitted right below the fridge.

We also have a warm air heating duct (insulated) in the same space. This morning I fitted an additional fan from a computer to the space to help dissipate the heat from the compressor.

I have also fitted 2 inches or 50mm of Kingspan foil backed foam to the underside of the fridge compartment.

On the same setting the fridge has dropped 5 degrees and is not constantly switching on/off. You would think the thermostat would regulate the inner temp to a set level. Apparently not !!!

I monitor the temperature using an electronic probe thermometer, which I got from Maplins (I think they are called radio shack in the states.) I have tried to find it on the web site but their search engine is about as much use as an ashtray on a motorbike.

When I find the part number I will post it.

Anyway as i sit here swinging on a buoy in Portsmouth harbour waiting for the sun to go down, I can assure you the beer is cold!!

Best regards.

Ant

ZhuHai · « **Reply #15 on:** July 12 2015, 23:35 »

@Baltic

The specs of this thermostat give a working voltage of 12V ±10% (10,8V - 13,2V).

When I installed it, the batteries were full and the solar panels were charging nicely so I guess the voltage was certainly above 13,2V.

The reading shouldn't fluctuate if the voltage stays more or less in the working range. We'll see but it will be certainly better than the previous mechanic thermostat which was quite erratic.

What I like with this thermostat is that I can set the temperature range when the compressor switches on/off. Let say the middle point is 4C then I can give a +-3C range so the compressor will start above 7C and will stop below 1C.

After few trials, I was able to reduce the running time of the compressor and still keep the fridge well cool.

I'm not an expert at all but seems to work good enough.

Nigel · « **Reply #16 on:** July 13 2015, 07:55 »

Quote from: ZhuHai on July 12 2015, 23:35

@Baltic
The specs of this thermostat give a working voltage of 12V ±10% (10,8V - 13,2V).

With items like this I normally fit a diode in series with the input, reducing it by about 0.6V.

Baltic · « **Reply #17 on:** July 13 2015, 09:44 »

I think diode is not solution for this issue...

But maybe LM7812 or similar.

Problem is.
Some thermostat. If operation voltage will change for example 12 V to 13 V.
Thermostat switching temperature will change as well....
Regulator is solution for that..
Yes..

And sometimes.
If you have heavy load same time when fridge try to start.
Voltage can temporary drop under 12V
12 V relay there in thermostat does not work any more as good as it should do...
(As well if you use 2 diode... 0.6 V drop per diode)

Just not that when acquire thermostat.
Extreme low price. Typically will cause bad engineering.

I have personal experience both of scenarios.
Non regulated and relay problems with low voltage.

Third thermostat.
Now I am happy.

andrejv · « **Reply #18 on:** July 25 2015, 08:14 »

@Baltic, is Htronic working ok with you?

Where did you place the controling unit (tsm 125) ? Somwhere hiden or so, that you see it? Can you maybe post a picture?

And where did your cable from the sensor exit the fridge box? Did you drill a new hole, or use some existing?

This year I replaced the faulty thermostath of vd15 with original one, but is now working even worse. So I bought TSM 125, which I will install this weekend, when I will recieve it on the boat. I'm currently cruising in Ionian.

Baltic · « **Reply #19 on:** July 25 2015, 17:08 »

Hi

Yes. Working ok.
No problems.

"Where did you place the controling unit (tsm 125) ? Somwhere hiden or so, that you see it? Can you maybe post a picture?"

Attached pic.
I think.
Need not to see display all the time.

The new hole drilled.

andrejv · « **Reply #20 on:** August 12 2015, 12:36 »

I changed the thermostate two weeks ago, and I used the Htronic. After two weeks of using it, I can say it?s working very well. I just added a 270 ohm resistor, to speed up the compresor. With no resistor compressor runs with 2000 RPM, with 270 ohms aproximately on 2500 RPM. Details on page 12 on this link: http://s3.amazonaws.com/zanran_storage/holod-konsultant.ru/ContentPages/2471207808.pdf

Zoso1 · « **Reply #21 on:** July 15 2019, 13:26 »

I am not sure if I will you through ths post as its pretty old. I am trying to connect the TSM 125 to my compressor but I cant get my head around the connections. Connecting directly into C and T does not poser it up. Any help in connecting it up would be greatly appreciated.

Baltic · « **Reply #22 on:** July 17 2019, 17:22 »

Hi.

Model number of the compressor ?
Check attached PDF´s...
Maybe there is some help..

lawrence_craig · « **Reply #23 on:** September 08 2019, 10:51 »

Just wanted to say thank you for the input into this thread. About to change the thermostat myself (MH1210) and was scratching my head a little but this helps a lot! Cheers.

Bav32 · « **Reply #24 on:** September 08 2019, 16:10 »

Quote from: Baltic on July 17 2019, 17:22

Hi.

Model number of the compressor ?
Check attached PDF´s...
Maybe there is some help..

Thank you for those pdf's. Is the resistor R1 the one inside the fridge? I mean the one at the cooling element?