Water Heater Control (Electric and Gas)??

miyzfrider wrote:

richardcoxid wrote:
No, so that on a decreasing bulk water temp the elect HWH element turns on first then, if the bulk water temp continues to drop lower then the gas comes on.

Great idea! I will add that to the off season project list. I like the idea of letting the electric do the work. Only concern I'd have is that in the event of no 110v electric, you'd have 10 degree cooler water. What are typical RV hot water heaters set to normally as far as a temp? 120 degrees?

Suburban WH have two sets of t-stats....normal & high temp set for electric and another set for gas
Normal is preset to open at 130*F. High is preset to open at 180*F
Lower normal preset available 120*F

Atwood uses only one set of t-stats....normal & high for both gas & electric
Normal preset to open at 140*F. High is preset to open at 180*F
An adjustable normal t-stat is available 110*-150*F

The t-stats are held tight against tank wall with tabs & springs. Coverings over t-stats are to insulate them from outside air

richardcoxid wrote:
No, so that on a decreasing bulk water temp the elect HWH element turns on first then, if the bulk water temp continues to drop lower then the gas comes on.

Great idea! I will add that to the off season project list. I like the idea of letting the electric do the work. Only concern I'd have is that in the event of no 110v electric, you'd have 10 degree cooler water. What are typical RV hot water heaters set to normally as far as a temp? 120 degrees?

richardcoxid wrote:
No, so that on a decreasing bulk water temp the elect HWH element turns on first then, if the bulk water temp continues to drop lower then the gas comes on.

Roger that!

No, so that on a decreasing bulk water temp the elect HWH element turns on first then, if the bulk water temp continues to drop lower then the gas comes on.

richardcoxid wrote:
Here is a hint when using Gas/Elect simultaneously.

The water temperature when using either Gas or Elect in most models of RV HWHs is controlled by non-adjustable (either on or off) Snap Stats. These are small thermostats about 1/2in in Dia and about 3/8in high exclusive of the push on connector terminals. On a typical RV HWH they are held in contact with the metal tank with a small (about 2in x 2in) piece of black foam tape. Normally the Gas stat will be on the gas burner side of the HWH and the elect stat on the elect heating element side of the HWH.

Carefully remove the tape and record the part numbers of the Gas “stat”. A wholesale electrical supplier or others should be able to cross-reference the “on” temperatures of each. Chose a new “GAS “stat (it’s a small dollar item) that turns “ON” about 10 degrees lower than the elect stat.

Now, when both Gas and Elect are turned “ON” , a small usage of hot water or normal heat loss will cause the elect stat to turn “ON” first (use the CG’s electricity not my propane). If the bulk temp. of the water continues to decrease then the Gas stat will turn “ON” for a very fast recovery time.

May you have fair winds and following seas!

Disclaimer- BE SAFE!- Be sure to de-energize the 120 VAC and the 12VDC before working on the HWH!

Don't you mean 10 degrees HIGHER?

Here is a hint when using Gas/Elect simultaneously.

The water temperature when using either Gas or Elect in most models of RV HWHs is controlled by non-adjustable (either on or off) Snap Stats. These are small thermostats about 1/2in in Dia and about 3/8in high exclusive of the push on connector terminals. On a typical RV HWH they are held in contact with the metal tank with a small (about 2in x 2in) piece of black foam tape. Normally the Gas stat will be on the gas burner side of the HWH and the elect stat on the elect heating element side of the HWH.

Carefully remove the tape and record the part numbers of the Gas “stat”. A wholesale electrical supplier or others should be able to cross-reference the “on” temperatures of each. Chose a new “GAS “stat (it’s a small dollar item) that turns “ON” about 10 degrees lower than the elect stat.

Now, when both Gas and Elect are turned “ON” , a small usage of hot water or normal heat loss will cause the elect stat to turn “ON” first (use the CG’s electricity not my propane). If the bulk temp. of the water continues to decrease then the Gas stat will turn “ON” for a very fast recovery time.

May you have fair winds and following seas!

Disclaimer- BE SAFE!- Be sure to de-energize the 120 VAC and the 12VDC before working on the HWH!

Winnebago puts both the water heater and the microwave on the same breaker. They put an automatic transfer switch in line. If the microwave is OFF, the water heater has power. If you turn ON the microwave, it automatically kills power to the water heater until the microwave goes OFF, then restores power to the water heater.

At least, that is how my Winnebago is wired.

My new Winnebago 5'er has both electric and lp switches inside. One issue I see with running electric is the increased amp usage. Running the water heater, A/C, and microwave I would assume would exceed my 30 amp hookup.

Several RV builders installed WH's without inside switches for the 110v side.

Most RV'ers find out which circuit breaker controls the 110v to the WH and use it instead of the safety switch (outside).

Lew

Old-Biscuit wrote:
Two separate controls.......each has their own set of t-stats
One set for electric (120V AC) and one set for LP Gas (12V DC)
The T-stats are mounted next to each other with High Limit on top and normal on bottom (Normal set for 130*F...High set for 180*F) Each High Limit has a 'reset button' which will trip power if high temp limit is reached (normal has failed etc.)

Both sources for heating can be ON for faster recovery
OR you can use just electric Or use just LP.

I'm surprised that there is just the one electric ON switch (outside compartment)....check under sink or monitor panel for another switch.
Thought that Suburban would have another switch by now......one switch is so old tech.

Just make sure that water heater tank is full of water before turning on that outside compartment switch...otherwise the element will burn out quickly as in just a few minutes.

My '07 has exactly what the OP is describing, one switch inside, marked DSI (direct spark ignition)for the propane & one switch out side on the unit it's self for electric, I know it's no longer new, but it's not that old.