Frost protection

[MtB]

I have a Webasto HL32-D warm air blower in ALDEBARAN.

 

It's old but works very nicely and has a thermostat on the wall. Trouble is, it's no use for keeping the boat just above freezing for long periods away. The reason is that the room stat only switches between high and low settings on the blower. It never turns the blower fully fully OFF so the batteries eventually die after a day or three.

 

Do modern Webastos/Mikunis/whatevers actually turn fully OFF when the room temp is satisfied and/or have a frost protection setting incorporated?

 

Or is there a way to make my HL32-D shut down completely then restart later if it gets too cold?

 

All advice most welcome.

 

(I'm not on a shoreline by the way, hopefully this is clear from my question!)

 

MtB

[eightacre]

Our Mikuni MX40 will turn on if the cabin temperature drops below 5 degrees - but this is due to the Danfoss controller rather than the Mikuni itself.

 

steve

[MtB]

Our Mikuni MX40 will turn on if the cabin temperature drops below 5 degrees - but this is due to the Danfoss controller rather than the Mikuni itself.

 

steve

Ah ok, so the Mikuni is totally OFF when the cabin temp is higher? This is what I need and my Webasto doesn't do. When cabin temp is higher it still runs on 'low' speed 24/7...

 

Thanks for your answer!

 

MtB

[rjasmith]

Mike,

 

I have no experience of Webasto etc thingys and maybe this is too simple but can you not use a thermostat to switch the 12v power to it?

 

Presumably it will go through its start up sequence automatically when powered up and doesn't need human intervention to do this?

 

It won't work I suppose if it goes into a lock out condition when power is removed but this wouldn't happen on a domestic oil fired boiler (well it doesn't on ours!).

 

If it can start up and run and then stop but remain capable of restarting with every power up /down cycle I would have thought you could do what you want like that.

 

Maybe use a separate frost protection thermostat to control the power plus perhaps a suitable relay if the start up currents are a bit hefty (glow plug?). It might be an idea to choose a thermostat with a large hysteresis so that the Webasto doesn't cycle too frequently.

 

Richard

[NMEA]

There is an independant frost protection module available quite cheaply (< £15) from Webasto for the more modern air and water heaters and I see no reason for it not to work with the HL series, not sure as I rarely even see one of those beasts nowadays. You must have a non marine version as the marine ones "control idle" is off state, the vehicle ones sample the incoming air for temperature regulation so their idle is low fan, not very power friendly and a fairly usual DIY or builder install to save a few quid, but penny wise pound foolish applies as with many things.

BTW, on an air heater that old you need to keep a close eye on the heat exchanger condition, if a water one goes permiable all you get is overheats or flame outs but with an air heater you get CO2 & CO pumped around the cabin, the designed service life before change is 10 years.

I have PDF workshop manuals and parts lists (not that many parts are still available) including cabling schematics which may help you, if you don't already have them I can send them if you PM me an email address

Edited November 14, 2013 by NMEA

[Naughty Cal]

I have a Webasto HL32-D warm air blower in ALDEBARAN.

 

It's old but works very nicely and has a thermostat on the wall. Trouble is, it's no use for keeping the boat just above freezing for long periods away. The reason is that the room stat only switches between high and low settings on the blower. It never turns the blower fully fully OFF so the batteries eventually die after a day or three.

 

Do modern Webastos/Mikunis/whatevers actually turn fully OFF when the room temp is satisfied and/or have a frost protection setting incorporated?

 

Or is there a way to make my HL32-D shut down completely then restart later if it gets too cold?

 

All advice most welcome.

 

(I'm not on a shoreline by the way, hopefully this is clear from my question!)

 

MtB

Sounds like you need a different control unit for it Mike

 

Ours has a frost stat for if the temperature drops below 5 degrees (as a back up to the electric heaters mainly) which is controlled via the 7 day timer. The webasto is completely turned off until the timer/thermostat turns it on due to either a set time or dropping below 5 degrees.

[MtB]

Mike,

 

I have no experience of Webasto etc thingys and maybe this is too simple but can you not use a thermostat to switch the 12v power to it?

 

Presumably it will go through its start up sequence automatically when powered up and doesn't need human intervention to do this?

 

It won't work I suppose if it goes into a lock out condition when power is removed but this wouldn't happen on a domestic oil fired boiler (well it doesn't on ours!).

 

If it can start up and run and then stop but remain capable of restarting with every power up /down cycle I would have thought you could do what you want like that.

 

Maybe use a separate frost protection thermostat to control the power plus perhaps a suitable relay if the start up currents are a bit hefty (glow plug?). It might be an idea to choose a thermostat with a large hysteresis so that the Webasto doesn't cycle too frequently.

 

Richard

 

Richard, thanks for these thoughts. Similar stuff was swimming un-verbalised through my furry brain anyway (including the one about the large hysteresis!) so I'll do some experimenting isolating the 12v and seeing if it locks out or re-starts itself on restoration of power. If it does then maybe a pair of thermostats would be in order, one to fire it up and the other (set much higher) to shut it down. Should be easy enough to figure out a circuit to do this, probably using another relay.

 

 

 

There is an independant frost protection module available quite cheaply (< £15) from Webasto for the more modern air and water heaters and I see no reason for it not to work with the HL series, not sure as I rarely even see one of those beasts nowadays. You must have a non marine version as the marine ones "control idle" is off state, the vehicle ones sample the incoming air for temperature regulation so their idle is low fan, not very power friendly and a fairly usual DIY or builder install to save a few quid, but penny wise pound foolish applies as with many things.

BTW, on an air heater that old you need to keep a close eye on the heat exchanger condition, if a water one goes permiable all you get is overheats or flame outs but with an air heater you get CO2 & CO pumped around the cabin, the designed service life before change is 10 years.

I have PDF workshop manuals and parts lists (not that many parts are still available) including cabling schematics which may help you, if you don't already have them I can send them if you PM me an email address

 

I'll be surprised if it's a non marine one as the boat was fitted out back in about 1990 to a very high standard with the best money can buy always selected. Even so, I think you must be right. Mine has a three position Off/Heat/Fan only Webasto branded control switch and a Webasto branded room stat. I have a PDF of the manual for it, about 60 pages IIRC! But thanks for the offer of your PDFs, sounds as though you have more stuff on it than me. I take your point about the HE. The fact that it is 13 years beyond it's design life is one more reason to change this for another unit along with it's almost total obsolescence which is why I was thinking of replacing it as a first option rather than a last. It hadn't occurred to me that CO might be getting distributed with the warm air, I'll do some testing with my gas analyser. Thanks.

 

 

Sounds like you need a different control unit for it Mike

 

Form what NMEA says I need whole new unit!

 

MtB

[NMEA]

 

Richard, thanks for these thoughts. Similar stuff was swimming un-verbalised through my furry brain anyway (including the one about the large hysteresis!) so I'll do some experimenting isolating the 12v and seeing if it locks out or re-starts itself on restoration of power. If it does then maybe a pair of thermostats would be in order, one to fire it up and the other (set much higher) to shut it down. Should be easy enough to figure out a circuit to do this, probably using another relay.

 

 

 

 

Never, Ever simply isolate the power whilst the heater is running, it can cause all sorts of damage, all control must include the ramp down cooling stage and can only be doine through the signal cables, it is not difficult and could probably be done with a £60 programable heatmiser room stat which also has a frost protection feature. They are available in battery powered "volt free" switched models so can operate all sorts of heaters with fairly simple modification to the heater signal loom.

[Phil Ambrose]

Never, Ever simply isolate the power whilst the heater is running, it can cause all sorts of damage, all control must include the ramp down cooling stage and can only be doine through the signal cables, it is not difficult and could probably be done with a £60 programable heatmiser room stat which also has a frost protection feature. They are available in battery powered "volt free" switched models so can operate all sorts of heaters with fairly simple modification to the heater signal loom.

Agreed with the comment about shut down, I had 2 stats as described on my previous boat controlling. Mikuni and a Propex. They worked perfectly and the 2 x AA batteries lasted 3 or 4 years IIRC

 

Phil

[MtB]

Agreed with the comment about shut down, I had 2 stats as described on my previous boat controlling. Mikuni and a Propex. They worked perfectly and the 2 x AA batteries lasted 3 or 4 years IIRC

 

Phil

 

You're missing the point Phil.

 

My thermostat (frost or otherwise) when satisfied does not result in the unit shutting down. The unit continues to run at low speed instead.

 

My question is about how to force the unit to go through the shut-down sequence when the stat turns OFF instead of it switching to running at low speed.

 

MtB