Fitting a frost station to a webasto heater

[tonyt40]

Hi. My boat has a webasto heater controlled by the digital timer. We don't live on board so at this time of year there are times when it will get very cold. I was looking at fitting a frost station to it to protect the domestic water services from freezing. Has anybody done this? I am sure it will be quite simple but just not quite sure of the wiring.

 

Thanks

 

Tony

[NB Lola]

I had it done for me. The guy said the instructions were quite clear

[nicknorman]

You don't say what type of webasto it is but assuming an evaporative type these are not well suited to being connected to a thermostat since they hate short cycling. If you are on shore power when away from the boat, it would be far better to use an electric heater on a thermostat / frost stat.

[Sea Dog]

My Eberspacher system has a thermostat with a frost setting. It's set to Max (30 something degrees) which effectively takes it out of the circuit for the reasons Nick suggests above.

[Tuscan]

We've got one, hopefully it's working now !

[Detling]

Put the thermostat outside so it comes on when the air temperature falls to 3 or 4 degrees. the boat will get toasty but the thermostat will still be cold. May be in the cratch under cover, but not in the engine room if that is where the heater is as that will warm up even if only a few degrees which could cause short cycling. Ideally you need a timer to shut the heater off after about an hour and preventing it starting again for another hour, thus keeping the boat above freezing but not at tropical island temperatures.

[NMEA]

There is a frost protection stat available as a Webasto accessory, they work well and don't make the heater cycle too much as they are wide differential.

 

http://www.webastomarine.co.uk/shop/vclose1.asp?prd=123548&cat=26

[tonyt40]

There is a frost protection stat available as a Webasto accessory, they work well and don't make the heater cycle too much as they are wide differential.

 

http://www.webastomarine.co.uk/shop/vclose1.asp?prd=123548&cat=26

Yikes... £85. I was thinking more of a £10 job from RS. Is there a combined thermostat / timer that can be set low or if not can I intercept the switch wire from the timer to the heater and fit something in there?

[mrsmelly]

There is a frost protection stat available as a Webasto accessory, they work well and don't make the heater cycle too much as they are wide differential.

 

http://www.webastomarine.co.uk/shop/vclose1.asp?prd=123548&cat=26

 

Now that looks a good bit of kit. Is it easy enough to fit?

 

Taa

[Naughty Cal]

They also do this one:

 

https://www.butlertechnik.com/webasto-heater-parts-c111/webasto-and-eberspacher-frost-thermostat-controller-4111263a-p1787

[tonyt40]

They also do this one:

 

https://www.butlertechnik.com/webasto-heater-parts-c111/webasto-and-eberspacher-frost-thermostat-controller-4111263a-p1787

That's more like it. Does anybody know how to connect it? I assume it would go between the live feed to the timer and switch wire?

[NMEA]

It's just a Honeywell T4360, you can but one on Amazon for under £18.00 You would need to install it in the trigger wire from the timer and install a bypass switch for normal usage, you would then need to turn the bypass switch off but leave the heating turned on as you left the boat.

Edited December 6, 2016 by NMEA

[nicknorman]

It's just a Honeywell T4360, you can but one on Amazon for under £18.00 You would need to install it in the trigger wire from the timer and install a bypass switch for normal usage, you would then need to turn the bypass switch off but leave the heating turned on as you left the boat.

However I suspect it's going to make the heater short cycle and as such will cost far more in maintenance over a couple of years than is saved by buying that domestic product as opposed to the proper item.

[NMEA]

However I suspect it's going to make the heater short cycle and as such will cost far more in maintenance over a couple of years than is saved by buying that domestic product as opposed to the proper item.

Entirely agree, but it's not what people want to hear, they just want cheap.

[jddevel]

So whilst I accept the logic about potentially "cycling" with the use of certain thermostats surely if the

frost stat is set at say 7or 8 degrees -as with a domestic boiler- this could be avoided? Failing which could

not one of you "wizards" design a gizmo where the boiler comes on at say 7 degrees and then switches off at say 14 degrees and will only switch on again when the temperature drops once again to 7? I`m sure this is possible but whether cost effective is another thing.

[nicknorman]

So whilst I accept the logic about potentially "cycling" with the use of certain thermostats surely if thefrost stat is set at say 7or 8 degrees -as with a domestic boiler- this could be avoided? Failing which couldnot one of you "wizards" design a gizmo where the boiler comes on at say 7 degrees and then switches off at say 14 degrees and will only switch on again when the temperature drops once again to 7? I`m sure this is possible but whether cost effective is another thing.

The problem with a small differential thermostat in a small space is that the latter can change temperature rapidly if, say, the sun comes out. What target temperature you set doesn't affect this problem.

 

But yes a system with a bigger differential could be designed or bought. Another way of dealing with it, which someonen I know has done, is to include a timer circui (NE555) that means that when the thermostat cuts in, the heater runs for an hour minimum. Cost pence, but requires an element of electronic capability that is most probably lacking in this techno-ignorant society that in general spends a huge amount of time on celebrity culture and zero time understanding the basics of how things work. We are doomed i tell you!

[jddevel]

Sound like old and cynical like me!!!