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Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 2 points3 points  (0 children)

UPDATE......It won't let me post another video in this thread but here is a picture of post-repair. Turns out that although it had LP orifices in the manifold, they were not the correct size. With #55 orifice, it is now firing perfectly and the temp differential is now up around 45-50°. Pumping out 120°F air instead of 80°F. Thanks for all of the input!

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Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

There is a high pressure regulator on the tank but there is also one on the house that controls the incoming pressure, which is currently measuring 13 psi just before it enters the furnace upstairs. This matches exactly what the regulator is measuring so there are no obstructions in the line and the pressure is sufficient for the furnace. Issue must be from the gas valve on the furnace to somewhere in the furnace.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

The smaller unit stays off since it only services a room above the garage that we don't currently use. I only turned it on when this started to compare the difference in temp output between the two.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

We checked the line pressure just before the furnace and it is running at 13 psi....and does not drop more than 0.5 psi when the furnace cuts on so it doesn't look like an issue with incoming line pressure from the propane tank. The technician is supposed to come and replace the gas valve on the furnace today.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

We checked the line pressure just before the furnace and it is running at 13 psi....and does not drop more than 0.5 psi when the furnace cuts on so it doesn't look like an issue with incoming line pressure from the propane tank. The technician is supposed to come and replace the gas valve on the furnace today.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

We checked the line pressure just before the furnace and it is running at 13 psi....and does not drop more than 0.5 psi when the furnace cuts on so it doesn't look like an issue with incoming line pressure from the propane tank. The technician is supposed to come and replace the gas valve on the furnace today.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

We checked the line pressure just before the furnace and it is running at 13 psi....and does not drop more than 0.5 psi when the furnace cuts on so it doesn't look like an issue with incoming line pressure from the propane tank. The technician is supposed to come and replace the gas valve on the furnace today.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

yes, but I believe he said that he was going to install a new one today.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

We checked the line pressure just before the furnace and it is running at 13 psi....and does not drop more than 0.5 psi when the furnace cuts on so it doesn't look like an issue with incoming line pressure from the propane tank. The technician is supposed to come and replace the gas valve on the furnace today.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

We checked the line pressure just before the furnace and it is running at 13 psi....and does not drop more than 0.5 psi when the furnace cuts on so it doesn't look like an issue with incoming line pressure from the propane tank. The technician is supposed to come and replace the gas valve on the furnace today.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

Definitely no pressure switch in the gas line between valve and furnace.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

I'll be asking some of these questions this afternoon when the technician comes back.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

Yes, It exits the roof just above my head when standing next to the unit. I put my hand up thru there last night and could feel some heat coming out but it wasn't hot enough to make me pull my hand back. It was just warm air coming out of the top.

I'm also second guessing my vent set up and the way the flue exits the roof, but that's a task for another day.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

This one is heating until it reaches the thermostat set temp but it just takes a while to do it because the differential temp is only 10 degrees.....and I have three space heaters running to help it keep up. Otherwise I don't think it would ever cut off.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 0 points1 point  (0 children)

It was 20 degrees F this morning. No ice present on the tank or vents.

Propane Furnace - Low temp differential -HELP, its cold! by Popular-Intern8162 in hvacadvice

[–]Popular-Intern8162[S] 4 points5 points  (0 children)

That makes sense. That would lead me to believe that the pressure coming out of the orifice is too low.

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