Propane regulator - delivery rates?

[hotponyshoes]

So,
I have a LPG 'instant' water heater
Ratings on the plate say 18 litre per min,
36kw.
Gas = LPG 2800pa

So, first problem is I can't find any 28mb lpg/propane regulators.
Propane all seem to be 37mb, I can only find butane ones for 28mb.

If I want to run from a standard calor type bottle can i use a 37mb?

Next, the flow rate of the propane regulators is either 1.5kg/hr or (next size up) 4kg/hr.

My rough maths works out that I need 2.6kg/hr for 36kw so do I just run a 37mb 4kg regulator?

 

[Kayos]

Not sure how interchangeable on your heater it is but some can work on either but some can’t

We use 4.1kg/hr regulators on boiler installs but you need 47kg bottles to sustain the take off rate

Your maths is pretty good, I don’t bother with smaller regulators as the bigger ones tend to be better built

 

[hotponyshoes]

When I ordered the heater it had a choice of either a propane version or natural gas.
I ordered the propane. The sticker on the unit states lpg which I think is pretty much the same thing.
It's the 2800pa gas pressure that's confusing me though as I can't find a regulator to match it?

 

[timgunn1962]

LPG equipment can usually be run on either Propane at 37 mbar or Butane at 28 mbar.

Butane is a bigger molecule (4 Carbons in the chain) than Propane (3 Carbons in the chain) and is denser, so less volume is needed and it takes less pressure to drive the same heating value through a jet, hence the lower pressure setting for Butane.

The whole 37 mbar Propane vs 28 mbar Butane thing was worked out decades ago by clever people and the pressures were specifically chosen so that "stuff" could run on either Propane or Butane and would give the same heat output. You'll be fine with the 37 mbar Propane.

Both gases can be described as LPG.