Have Big Max shop heater 75,000 btu new install won't light

You can try the maker or the other retailer.

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Comfort Glow CGS379 30,000 Btu Blue Flame Propane(LP ...

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This 30,000 BTU Propane(LP) & Natural Gas(NG) heater provides convective heat for the best whole room heating, up to 1250 sq ft. This heater is 99% fuel ...

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Could be a gas pressure issue and/or improper venting. Natural gas or LP (propane)?

simple answer is use one for a grill,it will be close to same pressure

First off, yes you can convert it to propane. The difference is that the orifice, which should be in the conversion kit, has a smaller hole for the gas to pass through and needs to be changed. Secondly, the air consumption on propane is greater than that of natural gas and for that reason you need to open the air venturi, usually to the max to allow the largest amount of air to enter. Don't overlook the pilot light as well, it also needs to have a different orifice installed. You can find new orifices and/or conversion kits at the store where you buy your propane, assuming it's not a big box retailer. Go to a local propane supply location for the parts. Another option is to go directly to the manufacturers home page and order the propane orifices.

First have you always had this connected to propane? There are different models for natural gas and for propane.If you connect a natural gas to propane the "jets" are way too big for propane. How did you clean the jets? IF you "drilled" them out they may be too large now. If you have adjusted the gas regulator, decrease gas pressure. I believe this unit has a combustion blower, be sure it is debris free on inlet and in fan, check for leaves. Make sure black smoke is not coming from debris built up inside of heater. Here is a link to a location for the complete manual for your heater: http://lawnandgarden.manualsonline.com/manuals/mfg/pentair_pool_products/400k_btu_hr.html

WITH PROPANE THEY NEED CLEAN AIR, I HAVE THIS PROBLEM WHEN I USE THEM IN A CRAWL SPACE, TRY TO PUT IT SOME PLACE WHERE IT CAN GET CLEAN AIR, GOOD LUCK PLEASE LEAVE FEED BACK IF THIS WORKS

I have the same problem with my Reddy heater 55-f. Is it thermal coupling or relay?

Big enough propane tank? proper pressure reducing valve on the propane? Check both of those.

I'm sure you can, contact the manufacturer and ask if they have a natural gas jet or orfice for your model heater, these are usually very easy to replace.

gas valve if smart valve or sensor if it is not the control board