A question for Chris Bryant or? (appliance op)
Mickey
Brother-in-law got a use MH a few weeks ago and trying to get everything in
shape to use the first time. As I was helping I noted several appliances
working differently than I'm used to so thought I would ask & see if what I
saw is normal operation.
First, the frig, a Dometic 1303. Looks like you have little choice in power
source and gas is in 3rd place. I noticed the gas flame wasn't going
straight up the flue but was bent and moving up the flue on the aft
(furthest away from gas selinoid) half of the opening. Is this correct or
does it sound like there might be an obstruction? Using a mirror from the
bottom I couldn't see up very far, an inch or two. Also due to the flame
shape the thermocouple was almost not in the flame. It took 3 tries before
the flame would stay lit. Could this be norm?
Second, the forced air heater, a Durotherm 65940. The heater lights within
a few seconds after the fan starts and when shut down, the fan stops the
same time as the burner. Is this norm for this heater?
TIA for any help you can offer.
Mickey
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Chris Bryant
>Got a question for Chris or anyone that has the knowledge.
>
>Brother-in-law got a use MH a few weeks ago and trying to get everything in
>shape to use the first time. As I was helping I noted several appliances
>working differently than I'm used to so thought I would ask & see if what I
>saw is normal operation.
>
>First, the frig, a Dometic 1303. Looks like you have little choice in power
>source and gas is in 3rd place. I noticed the gas flame wasn't going
>straight up the flue but was bent and moving up the flue on the aft
>(furthest away from gas selinoid) half of the opening. Is this correct or
>does it sound like there might be an obstruction? Using a mirror from the
>bottom I couldn't see up very far, an inch or two. Also due to the flame
>shape the thermocouple was almost not in the flame. It took 3 tries before
>the flame would stay lit. Could this be norm?
Nope- the burner probably has some crud in it. On this model,
I *think* if you look on the left hand side of the burner, you will
see a single screw holding it in place- I would take it out and make
sure it is clean- while you are at it, I would probably remove the
orifice and soak it in alcohol, for good measure.
>
>Second, the forced air heater, a Durotherm 65940. The heater lights within
>a few seconds after the fan starts and when shut down, the fan stops the
>same time as the burner. Is this norm for this heater?
I'm not quite understanding- will the furnace run through a
complete cycle, or does it cut off before it should? They used two
different methods with this furnace- the older ones have a thermal fan
switch, which will keep the fan running- but only after it heats up a
bit (it has to run for a few minutes)- the newer ones use a time delay
relay, and they should run on after the flame goes out, no matter how
long they have been on. If the fan comes on immediately when you turn
the thermostat up, it will be the fan switch type.
--
Chris Bryant
Bryant RV Services- http://www.bryantrv.com
Mickey
Chris Bryant <Bryan...@cfl.rr.com> wrote in message
news:iu1foukg6v8ko0hc4...@4ax.com...
The burner looks clean and there is a nice flame coming from all the slots
in the burner. The shape of the flame looks like there is air blowing it
towards the right and up into the flue. This appears to be the reason the
thermocouple isn't surrounded in the flame. Looking at the bottom of the
flue, it appears the flame has been this way for some time. The bottom of
the flue is corroded/rusted on the right half of the opening but you can
still see the original plating/coating on the left half. I'm sure the 3
tries to keep running is due to fact thermocouple isn't fully in the flame
due to the flame's distorted shape. Last night BiL called and said frig was
in the mid-30's with t'stat set just past mid-point. This sounds to me like
burner is delivering correct amount of heat that I wouldn't expect if
burner/orfice were partially plugged.
>
> >
> >Second, the forced air heater, a Durotherm 65940. The heater lights
within
> >a few seconds after the fan starts and when shut down, the fan stops the
> >same time as the burner. Is this norm for this heater?
>
>
>
> I'm not quite understanding- will the furnace run through a
> complete cycle, or does it cut off before it should? They used two
> different methods with this furnace- the older ones have a thermal fan
> switch, which will keep the fan running- but only after it heats up a
> bit (it has to run for a few minutes)- the newer ones use a time delay
> relay, and they should run on after the flame goes out, no matter how
> long they have been on. If the fan comes on immediately when you turn
> the thermostat up, it will be the fan switch type.
Since yesterday was the first time I saw the BiL's rig I can't say anything
about cycling. I turned the t'stat up to where the fan came on and by the
time I stooped down to look at the furnace the burner was lit. We let the
furnace run for about 5 mins then turned down the t'stat but not to the
t'stat's off position. As soon as the t'stat was turned down, both the fan
and burner shut off. I do see the thermal switch towards the top, front,
left side. Maybe the 5 min operation wasn't enough for the thermal switch
to function correctly. Will have to try again and let the furnace cycle by
its (or is that it's ;-) ) self.
>
> --
> Chris Bryant
> Bryant RV Services- http://www.bryantrv.com
Mickey
Chris Bryant
<<..>>
>>
>The burner looks clean and there is a nice flame coming from all the slots
>in the burner. The shape of the flame looks like there is air blowing it
>towards the right and up into the flue. This appears to be the reason the
>thermocouple isn't surrounded in the flame. Looking at the bottom of the
>flue, it appears the flame has been this way for some time. The bottom of
>the flue is corroded/rusted on the right half of the opening but you can
>still see the original plating/coating on the left half. I'm sure the 3
>tries to keep running is due to fact thermocouple isn't fully in the flame
>due to the flame's distorted shape. Last night BiL called and said frig was
>in the mid-30's with t'stat set just past mid-point. This sounds to me like
>burner is delivering correct amount of heat that I wouldn't expect if
>burner/orfice were partially plugged.
That is somewhat strange- but one of the reasons to soak the
orifice in alcohol is that the hole itself is rifled to spin the gas
flow. The spinning gas is supposed to hit the end of the burner and
bounce back some. It is possible for the rifling slots to be clogged,
and yet still flow the proper amount of gas.
But.. because of the indications that the flame has always
been like this, it could just be that the manufacturing tolerance is
off enough that everything is miss aligned just enough to cause it. If
it is working, I would be tempted to just not worry about it.
<<..>>
>Since yesterday was the first time I saw the BiL's rig I can't say anything
>about cycling. I turned the t'stat up to where the fan came on and by the
>time I stooped down to look at the furnace the burner was lit. We let the
>furnace run for about 5 mins then turned down the t'stat but not to the
>t'stat's off position. As soon as the t'stat was turned down, both the fan
>and burner shut off. I do see the thermal switch towards the top, front,
>left side. Maybe the 5 min operation wasn't enough for the thermal switch
>to function correctly. Will have to try again and let the furnace cycle by
>its (or is that it's ;-) ) self.
That's actually the limit switch, the fan switch is kind of
buried in the middle (front to back) lower (top to bottom) right hand
side.
Mickey
Never heard of the rifled jet before.
Mickey
Chris Bryant <Bryan...@cfl.rr.com> wrote in message
news:4n0hou8v6e6e7i6mc...@4ax.com...
>
> That is somewhat strange- but one of the reasons to soak the
> orifice in alcohol is that the hole itself is rifled to spin the gas
> flow. The spinning gas is supposed to hit the end of the burner and
> bounce back some. It is possible for the rifling slots to be clogged,
> and yet still flow the proper amount of gas.
> But.. because of the indications that the flame has always
> been like this, it could just be that the manufacturing tolerance is
> off enough that everything is miss aligned just enough to cause it. If
> it is working, I would be tempted to just not worry about it.
> >
> That's actually the limit switch, the fan switch is kind of
> buried in the middle (front to back) lower (top to bottom) right hand
> side.
>
>
> --
> Chris Bryant
> Bryant RV Services- http://www.bryantrv.com