Formula to calculate manifold gas pressure (LP gas conversion)

[chillerguy81]

Anyone know of a conversion formula to determine manifold gas pressure?

Example:

I ran into an old firetube boiler the other day that started it's life in 1962 as oil fired, converted to LP gas in the late 90's. Customer recently switched gas providers and now they can't get it to run right, so they called us. I found several problems with the fuel supply which is being addressed by the gas company before I return.

There is a burner manual onsite from the gas conversion but all numbers are for natural gas. So knowing the design manifold pressure @ design cfh of nat. gas can I covert that to LP gas, so that I will have an estimate manifold pressure at high fire, when I return to setup the burner?

Don't see many commercial LP gas burners around these parts!!

Thanks

[dandyme]

p 47, 48

may be what you want

[chillerguy81]

Thanks for the reply, great info in those manuals but not exactly what I was looking for. I had the flow conversion, looking for a pressure conversion if there is such a thing. May have to calculate the pressure drop through the gas valves etc. to figure out the manifold pressure.

[fxb80]

See if this helps.

[chillerguy81]

See if this helps.

Thanks for the reply, good info there too.

[hvacpope]

few years back I serviced 3 LP boilers with powerflame burners, the trick to get them to work right was to fine tune the burner on low fire using a combustion analyzer. what brand are the boiler/burner and whats the the problem?

here a link to the powerflame C burner, tons of good info. http://www.powerflame.com/index.php?option=com_docman&task=doc_details&gid=158&Itemid=68

[chillerguy81]

few years back I serviced 3 LP boilers with powerflame burners, the trick to get them to work right was to fine tune the burner on low fire using a combustion analyzer. what brand are the boiler/burner and whats the the problem?

here a link to the powerflame C burner, tons of good info. http://www.powerflame.com/index.php?option=com_docman&task=doc_details&gid=158&Itemid=68

I got it burning pretty good now. It is a York Shipley boiler and burner, I was just trying to gather some info before I got to the job. Thanks