Greenhouse Heating - Black Forest style!

Answered by Harrod Horticultural Posted in Category Greenhouse

Dear Martin

Currently we are trying to heat our new Rhino 2.4 x 2.4 greenhouse with a paraffin heater left over from a much smaller unit. It does struggle on very cold nights.

I lost a lot of plants over the last winter and now propose to run a heater during the exceptional cold winter periods. I am considering purchasing a new green house gas heater.

I note the Black Forest Catalytic Heaters are new on the scene and claim to be more efficient. Do you have any experience with this product & what are your views on the performance against other styles. I note that this unit comes in two outputs so which one do we require?

The specifications quote a gas consumption.  Is this figure applied when the burner is full on? If this is the case would it be more economical to run the 3.5kw at a lower thermostatic setting because it appears to have a larger radiation area & also the small one might be right on the limit for my greenhouse size?  

Could you please clarify about the regulator and hosing? Your website (specification below says regulator & hosing included)  your catalogue says not supplied. Which is correct?  

Sorry about the questions but having never used a gas heater before I thought best to ask a professional before I purchase one. My only experience is paraffin and trying to remember to turn it on and of morning and evening.  


Roger Attwood 

Dear Roger

Many thanks for your recent enquiry regarding the benefits of the new Black Forest Catalytic Heaters we stock.   

The Black Forest Catalytic heaters are superior to their gas and propane fired counterparts in theory, but we can’t comment on the results of using one of these heaters as we simply haven’t had the time to test and compare them! A true comparison would be very difficult anyway as you’d need to almost replicate the conditions – same plants, same weather, same feeding regime and same greenhouse – to obtain worthwhile data so we are really guided by the technical specifications, which are impressive.  

The main advantage of using the catalytic heaters over gas or propane is the efficiency  and cost saving. The catalytic burner has a thermal efficiency of over 99% and the warm air it produces is also enriched with CO2, which of course is ideal for growing plants. Normal gas, propane and paraffin heaters often do not attain complete combustion which can lead to a build-up of carbon monoxide, do not pump CO2 into your greenhouse and are generally less efficient to run.  

You’ll find that the gas consumption of the 2kw catalytic heater when operating on full burner (0.156kg/hr) compares favourably to similar sized models; and this size of heater will comfortably heat your 2.4m x 2.4m greenhouse so the extra financial outlay on a 3.5kw version will take a long time to recoup! We would advise lining your greenhouse with bubble insulation as this form of ‘double glazing’ can further reduce your heating costs by up to 30%.  

Finally, I can confirm that the catalytic heaters are supplied complete with a regulator and 1.4m of tubing. The discrepancy between the catalogue and website arose as originally, the heaters were not going to be supplied with these components but now they are. Unfortunately, the catalogue had already gone to print but amending the website copy was a simple task – so the website is correct!