Solved- Dry fired hot water heater

[shrimper]

Originally Posted by KyDan

You should have 12v on both wires at the t-stat/hi limit switch.
Put one meter lead on ground and test each wire while it's plugged
onto the T-stat.
12v on one side but not the other means the T-stat/hi limit is still
kicked out and possibly damaged. I doubt this but check it.
No voltage on either side means a fuse or loose wire or switch is still off.

You can also jump across the t-stat/hi limit to see if the burner
tries to light.
Be careful!! One side is 12v but the other t-stat is 120v AC!!
Make sure you know which is which!

Good luck!

Thanks for your reply.It is raining buckets here today so will check with meter later to be sure but seeing that the heating element is heating the water wouldnt it be a fair assumption to say that the 12v t-stat is fried?No fuses blowed..thats the first place i check when having any electrical issues also i ahve checked all wires for bad connections. Thanks again !

[KyDan]

IF the tank is already warm it might not be calling for heat.
You should have 12v on at least one end of the t-stat.
Check that 1st.

You can hold a jumper wire from terminal to terminal on the t-stat and
it should cause the gas burner to light. It takes a few seconds for
the control board to decide to light the burner so hold the jumper on there
for at least 15 seconds. If the burner does not light with the t-stat jumped
out you have other problems and it's probably not the t-stat.

You can check the t-stat/hi limit with an ohm meter.
Pull the wires off it or at least pull off one of them.
Then measure ohms across the 2 wire terminals on the t-stat.
It should read zero or very close to zero ohms.
IF it does the t-stat is good and it's calling for hot water.
If the t-stat measures infinite (same as if the meter leads aren't touching
anything) then the t-stat is still kicked out or it's bad OR the tank is hot
and the t-stat is not calling for heat.

This assumes the water tank is cold.
If you've been using electric and the tank is hot, it's possible the gas
t-stat is satisfied and it would read infinite ohms.

Most water heaters have a gas t-stat that is slightly lower set than electric.
This means if both are on once the tank gets hot the gas won't be used.
The electric element will cycle on and off to keep it hot unless you use a lot
of water. Then the gas will come on also.

Check for voltage at the t-stat and try the jumper test to see if
the burner lights. IF you don't have 12v at one end of the t-stat it's not
gonna light no matter what you do.

[shrimper]

Originally Posted by KyDan

IF the tank is already warm it might not be calling for heat.
You should have 12v on at least one end of the t-stat.
Check that 1st.

You can hold a jumper wire from terminal to terminal on the t-stat and
it should cause the gas burner to light. It takes a few seconds for
the control board to decide to light the burner so hold the jumper on there
for at least 15 seconds. If the burner does not light with the t-stat jumped
out you have other problems and it's probably not the t-stat.

You can check the t-stat/hi limit with an ohm meter.
Pull the wires off it or at least pull off one of them.
Then measure ohms across the 2 wire terminals on the t-stat.
It should read zero or very close to zero ohms.
IF it does the t-stat is good and it's calling for hot water.
If the t-stat measures infinite (same as if the meter leads aren't touching
anything) then the t-stat is still kicked out or it's bad OR the tank is hot
and the t-stat is not calling for heat.

This assumes the water tank is cold.
If you've been using electric and the tank is hot, it's possible the gas
t-stat is satisfied and it would read infinite ohms.

Most water heaters have a gas t-stat that is slightly lower set than electric.
This means if both are on once the tank gets hot the gas won't be used.
The electric element will cycle on and off to keep it hot unless you use a lot
of water. Then the gas will come on also.

Check for voltage at the t-stat and try the jumper test to see if
the burner lights. IF you don't have 12v at one end of the t-stat it's not
gonna light no matter what you do.

So i used a jumper wire to by-pass the 12v t-stat and the igniter now makes an attempt to light the burner with no luck.Lots of spark but seems to me that the gas valve is not opening.I had this problem first when i got the trailer and discovered that a wire was loose on the motherboard inside the trailer for the hw heater but i checked and this is not the problem now. Whats my next step? All fuses are good in the panel .Is there another fuse somewhere that im missing?

[Herk7769]

Originally Posted by shrimper

So i used a jumper wire to by-pass the 12v t-stat and the igniter now makes an attempt to light the burner with no luck.Lots of spark but seems to me that the gas valve is not opening.I had this problem first when i got the trailer and discovered that a wire was loose on the motherboard inside the trailer for the hw heater but i checked and this is not the problem now. Whats my next step? All fuses are good in the panel .Is there another fuse somewhere that im missing?

JUST TO BE SURE - You have removed power completely from the water heater for at least 1 minute between tries! After 3 "no light" events the board will shut off the gas until you do!

You have eliminated everything except propane and possibly the control board.

If you have 12 volts DC at the black wire on the solenoid; you have a propane problem

So either your propane is off; line clogged or crushed; bad propane solenoid valve (should smell gas if it is working); clogged flue (wasp nest) causing an over rich mixture (should smell gas when trying to light).

If you don't you have a bad control module.
http://www.dinosaurelectronics.com/Ignitor_boards.htm

[KyDan]

At this point it might be easier to shut off the 120v and run some hot
water so the tank cools and causes the gas t-stat to call for heat.
This should cause the board to spark.
This will also let us know the t-stat is ok.

I do not think there is another fuse.
IF the board is sparking trying to light the burner all that's missing
is the gas valve to open.

According to the schematic Lou posted below in msg 24 fig 7 below
one wire on the gas valve is grounded and the other wire comes from
pin 3 on the control board.

We're getting into an area where I'm not completely sure but I'd guess
you should have 12v at that wire on pin 3 of the control board while
the burner is trying to fire. Try tapping the gas valve with a screwdriver
handle while it's trying to light.
Check for voltage going to the gas valve while it's trying to light.
Plug and unplug the wire several times to clean the contact and make sure
it's getting a good connection--(NOT while it's trying to light!!)
Check the ground wire on the gas valve and make sure it's tight also.

On a previous trailer my water heater stopped working once and I removed
the wire plug from the control board and just re-plugged it several times
and it started working and did not give me any more problems for the
next 2 years we used it.

You know you can take your RV to any shop to get warranty service
on the water heater as long as they are an authorized repair shop
for that brand of heater. You don't have to go 1000 km back to the
place you bought it.

[KyDan]

G'morning Lou!!
Apparently we were both typing at the same time moments ago.

You say 12v on the black wire of the gas valve.
According to the schematic you posted below it's the brown wire.
The black wire is shown going to ground.
He should have 12v across the solenoid valve fer sure.
At least I guess it's 12v. I'm not completely sure if the board reduces
the voltage to the solenoid or passes the full 12v.
I may take a meter out to mine later this morning and test to see
what voltage actually goes to the valve. The schematic doesn't say.

[Herk7769]

Originally Posted by KyDan

You say 12v on the black wire of the gas valve.
According to the schematic you posted below it's the brown wire.
The black wire is shown going to ground.

ACK. You are correct of course BR is not BK.

Though with not enough coffee and the dog waking me up at 5:45 to go out this morning..... It looked the same to me.

[shrimper]

Originally Posted by herk7769

JUST TO BE SURE - You have removed power completely from the water heater for at least 1 minute between tries! After 3 "no light" events the board will shut off the gas until you do!

You have eliminated everything except propane and possibly the control board.

If you have 12 volts DC at the black wire on the solenoid; you have a propane problem

So either your propane is off; line clogged or crushed; bad propane solenoid valve (should smell gas if it is working); clogged flue (wasp nest) causing an over rich mixture (should smell gas when trying to light).

If you don't you have a bad control module.
Ignitor Board Index page

I can say with almost 100% certainity that it is not a propane problem.I filled both tanks with fresh propane 2 weeks ago.Furnace works fine and so does the range and oven.It fired up immediatly on gas on our first night in the trailer this year and as you know i fired off on propane with no water in the tank.Do you think that the dry fire did something to control board?

[shrimper]

Originally Posted by KyDan

At this point it might be easier to shut off the 120v and run some hot
water so the tank cools and causes the gas t-stat to call for heat.
This should cause the board to spark.
This will also let us know the t-stat is ok.

I do not think there is another fuse.
IF the board is sparking trying to light the burner all that's missing
is the gas valve to open.

According to the schematic Lou posted below in msg 24 fig 7 below
one wire on the gas valve is grounded and the other wire comes from
pin 3 on the control board.

We're getting into an area where I'm not completely sure but I'd guess
you should have 12v at that wire on pin 3 of the control board while
the burner is trying to fire. Try tapping the gas valve with a screwdriver
handle while it's trying to light.
Check for voltage going to the gas valve while it's trying to light.
Plug and unplug the wire several times to clean the contact and make sure
it's getting a good connection--(NOT while it's trying to light!!)
Check the ground wire on the gas valve and make sure it's tight also.

On a previous trailer my water heater stopped working once and I removed
the wire plug from the control board and just re-plugged it several times
and it started working and did not give me any more problems for the
next 2 years we used it.

You know you can take your RV to any shop to get warranty service
on the water heater as long as they are an authorized repair shop
for that brand of heater. You don't have to go 1000 km back to the
place you bought it.

"On a previous trailer my water heater stopped working once and I removed
the wire plug from the control board and just re-plugged it several times"

I had the same problem first when i brought trailer home,the wire had disconnected and same thing was happening all i just plugged it back in and has been fine ever since.Works fine on electric ,tank is cold now.If the control board was fried wouldnt it affect the 120 v side as well?the t sat for 120v is fine as i tested it for continuity but the 12v gas side was burned out .

[KyDan]

Originally Posted by shrimper

If the control board was fried wouldnt it affect the 120 v side as well?the t sat for 120v is fine as i tested it for continuity but the 12v gas side was burned out .

As I've said before-- and LOTs of folks have trouble with this...

The 120v AC heater is TOTALLY INDEPENDENT of the LP gas burner and
control board.

They are not connected anywhere at all period.
The ONLY thing the electric and gas heat have in common is the tank
of water they are trying to heat.

They have separate power sources and separate off/on switches and
separate T-stat/hi limit switches.
There is NO control board for the AC electric heater.
It's simply a heater- inside the tank, a thermostat/hi limit switch- outside
the tank and a black off/on rocker switch which is usually found in the
outside hatch near or even behind the gas burner tube.

OK so you now have electric hot water working OK yes???
You have it shut off so the tank is cold-- good.

You say the gas t-stat was burned out???
Have you replaced it??
Have you tested for 12v at one end of the t-stat???
I guess you do have that because you said earlier that you jumped
across the gas T-stat and the burner tried to light-- you heard and
or saw the spark jumping???

IF you had spark all you need is for the gas valve to open.
You need to put a meter across the wires for the gas burner valve and
see if you have voltage AT the burner valve while it is sparking.
Set your meter on DC scale and you should find 12v across the gas
valve while it's sparking.

1-- If you do have voltage but don't smell gas the valve is stuck or burned out.
2-- If you don't have voltage at the gas valve this would indicate a probable
bad control board.

I think you have narrowed it down to 1 or 2.

It's awfully hard to trouble shoot your water heater from my basement but
that's my opinion.
I'm not gonna tell you to go messing with the LP gas part of the system.
If you mess up and have a leak or other problem that causes you a fire
or other grief I don't want the blame!

I'll tell you that I'd not be afraid to continue but I've got 37 years of
industrial maintenance under my belt and feel confident doing that kind
of stuff.
If you don't feel confident, it's getting closer and closer to time to go
to a repair shop.

[shrimper]

Originally Posted by KyDan

As I've said before-- and LOTs of folks have trouble with this...

The 120v AC heater is TOTALLY INDEPENDENT of the LP gas burner and
control board.

They are not connected anywhere at all period.
The ONLY thing the electric and gas heat have in common is the tank
of water they are trying to heat.

They have separate power sources and separate off/on switches and
separate T-stat/hi limit switches.
There is NO control board for the AC electric heater.
It's simply a heater- inside the tank, a thermostat/hi limit switch- outside
the tank and a black off/on rocker switch which is usually found in the
outside hatch near or even behind the gas burner tube.

OK so you now have electric hot water working OK yes???
You have it shut off so the tank is cold-- good.

You say the gas t-stat was burned out???
Have you replaced it??
Have you tested for 12v at one end of the t-stat???
I guess you do have that because you said earlier that you jumped
across the gas T-stat and the burner tried to light-- you heard and
or saw the spark jumping???

IF you had spark all you need is for the gas valve to open.
You need to put a meter across the wires for the gas burner valve and
see if you have voltage AT the burner valve while it is sparking.
Set your meter on DC scale and you should find 12v across the gas
valve while it's sparking.

1-- If you do have voltage but don't smell gas the valve is stuck or burned out.
2-- If you don't have voltage at the gas valve this would indicate a probable
bad control board.

I think you have narrowed it down to 1 or 2.

It's awfully hard to trouble shoot your water heater from my basement but
that's my opinion.
I'm not gonna tell you to go messing with the LP gas part of the system.
If you mess up and have a leak or other problem that causes you a fire
or other grief I don't want the blame!

I'll tell you that I'd not be afraid to continue but I've got 37 years of
industrial maintenance under my belt and feel confident doing that kind
of stuff.
If you don't feel confident, it's getting closer and closer to time to go
to a repair shop.

First of all i would like to Thank you for your help it was really apreciated and helpful.I could not get this off my mind and had to figure it out so i went out and checked each wire and found one of the brown wires going to the solenoid to open the gas valve im assuming was broken,i prob done it while i was taking the cover for the t-stats off.I repaired that wire,hooked it back up,jumped the 12v t-stat and she fired up with no problem at all which made me a very happy camper(no pun intended lol)So all and all im out a 12v t-stat which cost $20 im guessin.I live in a small town in Northern Newfoundland,Canada so i dont have access to much when it comes to tech. help /rv parts etc.But with your guys help i now know basically everything to check/troubleshoot with HW heater.It will come in handy im sure one of these days.So once again Thanks alot and happy camping!! p.s. if your ever in St.Anthony,Newfoundland ,Canada look me up,fresh seafood dinner on me !!! Google us ,we have lots of visitors from the U.S !

[KyDan]

Google search for Suburban 232319
This is the 140 deg F 12v Suburban thermostat/hi limit.

I found several places selling it. I'm sure you'll find one that ships to
Canada and your good to go.
Any RV seller with a decent parts dept should have it.
Online cost anywhere from $18 to $26 US.

I'm going to mark this thread Solved!!

We are very glad to have been of assistance.

I can't rule out a Canada trip some day.
Wife is maybe going to retire in a year or 2.
When that happens I want to do some serious traveling.
Touring Canada is in my "bucket list"!

PS. Be SURE you replace the thermostat cover carefully.
I believe it has a gasket and 3 screws. Replace all 3 screws carefully and
fully. That cover is there to air seal the outside burner/exhaust area
from the inside water tank living space.
It could be possible for exhaust carbon monoxide gas to get inside your
RV with the T-stat cover loose or missing.
It's IMPORTANT to be sure it's back in place before you use the
gas heat!!

Happy Camping!