Frost thermostat problems

[rsk289]

Sorry, this is a slightly unconventional question...
I have two wall-mounted Calorex dehumidifiers in my garage/workshop. These have fan heaters (2kw, I believe) built-in to them. The idea is to stop the dehumidifiers from freezing up. They were supplied with very cheap 2-wire thermostats with dials reading from 0-30˚C, which would turn the heaters on at around 7-8˚C no matter how low I turned the dials. This ran up a stupid electricity bill over last winter, so I replaced the stats with Corgi frost thermostats, supposedly rated at -5 - 10˚C, which I hoped I could set low enough to set the heaters to come on at 3-4˚C. No such luck - one won't come on at all, and the other comes on at 8˚C no matter where the dial is set.
Question - is there such a thing as a decent quality 2-wire no-volt thermostat that could reliably be set to power up these heaters at around 3-4˚C? These things have only cost around a tenner so I expect to need to pay more. I am no expert, as I'm sure you can tell, so advice would be very welcome.
Roger

 

[garygvl]

corgi manufacture a frost stat hmmmmmm

 

[Rob Foster]

honeywell make most things really well but often are not cheap. Rob Foster aka centralheatking

 

[rsk289]

Thanks - I always wonder about control devices that cost under a tenner. I'll have a look at Honeywell, it'll save me a lot more than the cost of a couple of thermostats and maybe stop 'management' complaining about the electricity bills.

 

[Rob Foster]

Thanks - I always wonder about control devices that cost under a tenner. I'll have a look at Honeywell, it'll save me a lot more than the cost of a couple of thermostats and maybe stop 'management' complaining about the electricity bills.

The average home has over 10 honeywell products in it, in a building you are never more than 3m from a Hwell product, every turbo in every vehicle is fitted with a honeywell one ..under license. This is why I use them and incorporate them into my designs ...great quality
Rob Foster ....centralheatking

 

[rsk289]

Hmm. I don't seem to be able to find a Honeywell frost thermostat for a no-volt system. The Calorex units require no-volt switching and 2 wire connections. There's not much choice for this spec, I'm finding. Anybody got any ideas?

 

[rpm]

Try the sparkie forum?

 

[rsk289]

Thanks, I'll give that a go.

 

[Harvest Fields]

The average home has over 10 honeywell products in it, in a building you are never more than 3m from a Hwell product, every turbo in every vehicle is fitted with a honeywell one ..under license. This is why I use them and incorporate them into my designs ...great quality
Rob Foster ..centralheatking

Any chance of posting the proof to these facts Rob?

 

[Welder]

Hmm. I don't seem to be able to find a Honeywell frost thermostat for a no-volt system. The Calorex units require no-volt switching and 2 wire connections. There's not much choice for this spec, I'm finding. Anybody got any ideas?

Use a 240VAC relay! Use the stat to power the coil of a 240V relay and then use the relay contacts as they are no volt. Simples!

 

[Burger]

Siemens RDH100RF/SET Wireless Thermostat & Receiver - 23495 | BES.co.uk

One of these may work, they use a mains connection for power and volt free switched live. Only trouble is the lowest you can set is 5 degrees.