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Jacksonjack · 06-10-2019, 05:49 PM

Bought a 2015 Dynamax 320 . Love the rig but the water heater doesn’t work.
It had the Girard GSWH-1m. I pulled it and flushed it out and got good water flow. But could never get it to power up. I know they didn’t get great reviews so I figured I would swap it out with the newer version . It came today, so with the joy every guy gets when the big brown truck shows up I went to put it in. Went in pretty easy went to fire it up and nothing......
Called Girard and they had me pull cover. Had a red light. He said it usually had something to do with the power source or the ground. I thanked him and went about figuring out what’s up.
Went and pulled a battery from the garage. Hooked up the water heater to my known good battery, POW , got hot water. Tested the volts on the battery and it read 12.25 volts.
Tested the wires that had been hooked up to the water heater before, 12.45 volts. Thought maybe I had a bad connection the first time, so hooked it back up to the coach wiring, boom, water heater won’t come on .
So why won’t this #$*@#$ thing work .
Here is a pic of the wires
These are what the old hot water heater were hooked up to.

jacwjames · 06-10-2019, 06:20 PM

Usually the water heater is controlled by a switch. Any chance the switch was off?

Jacksonjack · 06-10-2019, 06:51 PM

No , the way the Girard works is it’s hooked to a power source. There is a switch outside on the water heater, then there is a switch that controls on/off and water temp That comes off the back of the water heater.
I can’t figure out why I get a green light on the water heater when hooked to a battery but get a red light when hooked to the coach power .
Would a bad ground still show 12.45 volts but throw the water heater off ?

Ljwt330 · 06-10-2019, 07:36 PM

Quote:

Originally Posted by Jacksonjack

No , the way the Girard works is it’s hooked to a power source. There is a switch outside on the water heater, then there is a switch that controls on/off and water temp That comes off the back of the water heater.
I can’t figure out why I get a green light on the water heater when hooked to a battery but get a red light when hooked to the coach power .
Would a bad ground still show 12.45 volts but throw the water heater off ?

Short answer, yes, a bad ground can result in insufficient voltage.

When you connected directly to a battery, you likely connected directly to the pos and neg terminals giving full voltage and amperage to the heater. In the coach, you have to connect through the wiring and a poor connection at either the pos or neg lead can result in a voltage drop.

Jim18655 · 06-10-2019, 08:27 PM

Measure the voltage while connected and turned on trying to run.
There's a big difference between voltage with a meter and voltage under load. Current draw can lower the power (volts times amps) available to the heater.

Jacksonjack · 06-10-2019, 09:11 PM

The other thing I thought of was I once had a Jeep with a bad ground. You could turn the key on and all the lights would come on. Once you tried to crank it everything would shut off. Turned out to be bad battery ground cable . I’ll hook it back up and see if the volts drop when I turn on the hot water heater .

Jacksonjack · 06-11-2019, 06:33 AM

Went out and did some more testing this morning. Hook the water heater up to the coach wiring system and got the same red light. Then I disconnected the ground side and ran a wire straight to the batteries of the coach while leaving the positive side hooked up to the coach wire. Same problem. Then I hooked the water heater back to the ground side of the coach wiring system but ran the positive side straight to the coach batteries, boom, green light good to go.
So .... I could easily fix this by running a hot wire from the battery to the water heater and just making sure I turn off the water heater off when not in use. But it would sure be nice to know what’s going on with the coach wiring ?? Could a broken wire on the hot side cause it to read good on the multimeter but no good when hooked to the hot water heater. Remember this is a Girard tankless so it’s not like the electric is used to heat the water and pulling a large load, it basically is just used to run the igniter and micro processor in the water heater .