I have a question about my heater.
Its a relatively new (within the last 3 years) 200,000 BTU Modine heater that is suspended in the greenhouse from the ceiling. It has electric ignition for the pilot light.
It replaced an older model heater that had the old inefficient manual light pilot light that burned 24/7.
When it was installed, it was connected to the existing system that vents to the outside. The chimney/flue was very tall and pretty big diameter.
Hurricane Irma knocked my flue off, and I had a new one installed. The new one is a smaller diameter and not as tall.

My issue is this.
I have started to hear a kind of bang or pop (its a loud noise) whenever the heater goes is on.

Before I had the new flue/vent put on, I never heard this noise. For 3 years.

I read on the internet that when a 'furnace' makes this noise as the heater STARTS, it can mean 'delayed ignition' of the gas, and that isn't good.

I also read that if it happens when the heater has been going and turns OFF, it is usually just the metal in the duct and flue work contracting because it expanded when it heated up.

I tried to test my system to see if I could tell when it was happening in the on/off cycle. But I have to stand outside the greenhouse, manipulate the thermostat, and hear from there. Not from in by the heater. As near as I can tell, it happens only sometimes when the heater comes on. But not every time it starts.

Are there any heater pros here who can advise me?

Well, here is a lesson for anyone with a propane greenhouse heater. DOn't ignore those weird sounds. Turns out after I called the dude who works on electrical and gas in my greenhouse that the burners were partially clogged with soot, causing the gas to be released through the little openings in an irregular fashion, and causing gas to pool before the pilot lit it up. Causing basically a 'roll out' of flame inside the heater and a kind of miniature fireball explosion. Not good. Had to take the heater apart and take out and clean the burners(there are 9) and the pilot light orifice and igniter tip. Back to working normally. But could have potentially caused a lot of bad, bad trouble.

Good advice Gina

Glad to hear you caught the problem before anything serious could happen.

My last heater (a Modine 250 000 BTU propane heater I had from 2003-2015) flamed out and caught fire due to rust accumulation. It was on a 20F night, when there was a string of more than one 20F nights. I lost plants. Regular heater maintenance is imperative

Modines are one of the cadillacs of large greenhouse heaters, but I guess with all the humidity you can't avoid the rust, so you are spot on about regular inspections and maintenance.

That is what my heater guy says. Being outdoors 365/24/7 and it being so humid most of the time will rust it out eventually on the inner workings just like you were misting it with water on a regular basis. I fired it up early in the season before it got cold and it was ok, even worked fine up until about a week or so ago, then I guess the soot buildup loosened up just enough to start intermittently clogging the gas burners. The bad thing is you kind of have to disassemble the thing to get the burners out to clean them.

Hi guys, I've heard about heaters that run on solar power. If you know anything about this, please share your experience. To update my post, I want to say that I found information about this on Google and watched a few videos on YouTube. But I still want to get live reviews to know if it's worth buying. In the meantime, I'm using the old method to heat the greenhouse. I cover the plants with a tarp and put hot water bottles under it, which helps keep them warm until morning. And if we talk about a heater for bedrooms, I recently found Dehumidifier critic blog where there are reviews of heaters. If you can advise me on the best one, I will appreciate it.

Never heard of that.

I could not imagine they would give much heat unless you are in a very temperate climate, although I would be very interested in hearing more.

I had to get a new part for it, and am getting it installed hopefully tomorrow...good thing there is no cold weather on tap for at least 10 days

Gina1960 said:That is what my heater guy says. Being outdoors 365/24/7 and it being so humid most of the time will rust it out eventually on the inner workings just like you were misting it with water on a regular basis. I fired it up early in the season before it got cold and it was ok, even worked fine up until about a week or so ago, then I guess the soot buildup loosened up just enough to start intermittently clogging the gas burners. The bad thing is you kind of have to disassemble the thing to get the burners out to clean them.

I think the standing pilot keep them dryer inside . In the off cycle

I have a 500 gal propane tank to heat the greenhouse. The heater does need maintenance and burner replaced a few times. It's very dependable when growing plants and flowers in the feb. for the Annual state flower show competitions. And great for starting seeds for spring plantings. It's connected to a thermostat and vents opened and closes according to temps set, as well as fans coming on and off. Air vents are also installed to and bottom and tops of the greenhouse. For safety reasons it's important to maintain good ventilation. I also heard that some plants don't like butane fumes if the greenhouse is not well ventilated combined with ventilating fans. The fumes can cause plants to yellow if not properly ventilated. I keep a battery operated CO and Propane detector in the greenhouse just to be safe.

Gina did the new part get installed your heater yet? Hope the greenhouse is running well, purring like a kitten. You have so many gorgeous collections. I drool every time you post pics from your greenhouse. How often do you need to clean the sides. I power wash in summers. Of course mine does not have the permanent set up or as beautiful as your greenhouse. So summer when it empty it's a good time to straighten things up and power wash the slimy green off.

Yes! I had to replace the pilot light assembly and the burners but still QUANTUM cheaper than a new heater. Its working great now!!!!!!

Glad to hear the greenhouse heater was fixed and all set for the winter. What size is your propane tank? Do you have the new safety set up on the tank?

I don;t know what the new safety set up is. Its 250 gallons, its been in place since 2002

The safety valves... with the function of a safety relief valve is to keep a propane tank from rupturing from excessive pressure buildup. Propane tank relief valves were known as pop off valves or relief valves. The state has made these safety valves mandatory here especially due to the summer fire season.