As part of my annual water heater service, I decided to upgrade our propane-only unit to dual function by adding a electric heating element. I chose the Hott Rod HR-6 universal kit for 6 gallon tanks, and added the PSK1 Hott Rod switch kit for convenience. The installation is fairly simple, and can be accomplished with a few hand tools. The photos below show the steps.
With heater off and cold, remove the drain plug and drain tank. Flush out sediment. Install adapter bushing in the drain hole, then add the heating element. Attach the electric power cord. This was where I hit my first snag. On our Atwood heater, the propane supply line runs close by the drain plug. I was able to install the heating element without any problem, but the electric plug, which has to snap on the end of the element, was a VERY tight fit. By trimming the rubber lip on the plug, I was just able to "persuade" it into proper position. Any tighter and it would not have worked.
Drill a 1/2" hole through the heater front plate sheet metal, then feed the power wire through the hole. Put the split flex loom stuff on the wire to protect it. Next, find a spot to mount the thermostat control. This is the 2nd place where I had a small difficulty. The thermostat has to stick to the metal water tank, and on our coach, access to the tank is VERY limited. I finally decided to try a spot just behind the steel beam that supports the water heater. I cut the cardboard tank cover with a box cutter and made a flap, which I then peeled back. The fiberglass insulation stuck to the flap, exposing the metal tank. Used steel wool and alcohol swab to clean up the mounting place.
Before mounting the thermostat, you need to set the desired temperature, hook up the power wire, and (if you are going to use one) connect the switch. I set the temp on 140 degrees (no kids) to help extend showers. The wiring harnesses supplied in the kits are very good quality, and go together easily. You only need to crimp one connector (if you use the switch). Connect the wires to the thermostat, and then peel the paper off the double sided tape, and stick the thermostat to the tank. The instructions say to let it "cure" 24 hours, so I folded the flap back over the thermostat and held it all tightly in place with a stick of wood. Quit for the day.
Next morning, all I had to do was mount the switch and tidy up the wiring. Electrical power was easy, because I already have a extension cord in our water pump bay (for Winter heater). I thought about trying to put the switch somewhere inside the coach, but after looking at how difficult it would be, decided to pussy out and mount the switch in the heater bay. I figure we will only use the electric heat when we are plugged into shore power - otherwise we'll use propane. It won't be any problem popping open the bay door and flicking the switch on after we park and get the coach hooked up.
I mounted the switch on the support beam under the water heater. Collected all the wires and tired them up out of sight behind the water heater. Filled the water heater with water (VERY IMPORTANT), then plugged the heater cord in and turned on the switch. The switch lights up when the power is on. I could hear the element come on and start to burble, so I knew it was working. Went inside, had some dinner. Came out about 45 minutes later, and checked hot water temp at the bathroom faucet with digital meat thermometer: 140 degrees EXACTLY!
I think this will be a very nice addition to our coach. It is quiet, and it will save on the use of propane when we have full hook-ups. If we need hot water REALLY fast, we could use both the propane and the electric element. Several reports I read online said this combo will heat water almost as fast as you use it, and can extend showers almost indefinitely. Can't wait to try it out! ^.^d
Amazon.com: Diamond Group (HR6) Universal Hott Rod - 6 Gallon Capacity:... (http://www.amazon.com/Diamond-Group-HR6-Universal-Hott/dp/B002SSIBSA)
Amazon.com: Diamond Group PSK1 Hott Rod Power Switch Wiring Kit: Automotive (http://www.amazon.com/Diamond-Group-PSK1-Switch-Wiring/dp/B003YJLM2E/ref=pd_bxgy_263_2?ie=UTF8&psc=1&refRID=51YN6ET126GCTY60K8GH)
Nice write up Chuck.
Another bonus is it's a completely 100% independent system so you now have a back up in case something goes wrong with the propane side. If you were to buy a new propane/electric unit it wouldn't be a 100% backup - the electric is controlled with the same circuit board as the gas. The older combo units (original to my '91) had the electric controlled independently like the hot rod. Sometime between '91 and 2006 they changed the electric control - no doubt to save $.
Thanks, John. I never really though about the "redundancy" factor, but that's a good point. Our 23 year old water heater is still working perfectly - that is why I was willing to spend $100 to upgrade it. But it is surely living on borrowed time - so having a alternate heat source could be a good thing. Until the tank explodes... :o
And speaking of exploding tanks, I also installed a new pressure/temperature relief valve at the same time as the new heating element. Old one was totally frozen. I figure if I'm going to have a double heat source in our water heater, it's good insurance to have a operable safety device.
0121325 - Watts 0121325 - 1/2" LF1XL-4 T&P Relief Valve, Lead Free (150 psi) (http://www.supplyhouse.com/Watts-0121325-1-2-LF1XL-4-TP-Relief-Valve-Lead-Free-150-psi)
Update: Good thing I replaced the relief valve on the water heater. The old one was completely frozen, and would not open. After I got the Hott Rod installed, I let it run for about 1/2 a day while we were in town. When we got back, I saw a small puddle of water on ground below the water pump/heater bay door. Opened it up, and everything looked OK, but obviously some water had been released from the safety valve. Went inside, and checked the hot water temp again with my meat thermometer. It was reading 160 degrees! The first time I checked and saw 140 degrees I guess I hadn't let it run long enough. Anyway, no harm done - the safety valve did its job and relieved the excess pressure in the tank caused by the high temps (I guess). I turned the thermostat on the heating element down a bit, and will keep checking it until I get it lined out at about 140 degrees.
I didn't like the fact that when the safety valve opens, the water drops right down onto the burner assembly. Thought about it a while, and decided to build a little manifold to divert the water. Photos below. The CPVC pipes are all just stuck together friction tight, so they will be easy to disassemble if ever required. Now, when/if water vents, it runs down the joint between the two bay doors and onto the ground. I like that better.
I was a little concerned about the relief valve opening, but after searching the subject with Google, my concerns are dispelled. It is not unusual for these valves to open - in fact, if they DON'T open once in a while, then you might have a problem. One thing that will reduce the frequency of this happening is a pressure tank in the water system. The tank will absorb the pressure fluctuations in the water lines, and often eliminate any opening of the safety valve. I removed the pressure tank when I installed our new water pump, but I also anticipated the possibility that I might want to reinstall it at some future date. Since, with the tank in place, it was rather crowded in the water pump bay, I decided to move it. But where? I finally decided to put it in the bathroom cabinet below the sink. The far-back corner of the cabinet was not being used, and it would not be in our way there. I rigged up a bracket to "hang" the tank from the shelf. It is clamped to the adjacent water lines to prevent any sway, and slightly supported from the bottom with a block of foam. Seems very secure. If I do decide to hook it up, I will just "T" into one of the water lines going to the sink with the original connector line.
UPDATE:
The Hott Rod works exactly as advertised. On a recent 5-week trip to the Pacific NW, we put the 110V heating element to good use. The duplex outlet I am using for power is "hot" on shore power or when running our generator. It is NOT powered from the inverter, so no worry about draining our batteries with this device. I left the Hott Rod turned on the whole trip. If we were using our generator going down the road (to run roof A/C units), then the water tank was being heated. Or, when we arrived at a campground, as soon as we plugged into shore power, the water heater started heating. The ONLY time on the whole trip that we used the propane water heater was for showers. We found that having BOTH propane and 110V heaters running could greatly extend our shower time. Otherwise, the electric element (plus the motoraid heating loop while driving) was all we needed. ^.^d
I decided to go ahead and connect the pressure tank before our recent trip. The tank functioned perfectly on the trip, and "played nice" with our new Shurflo 4008 water pump. It provides quite a bit of water flow before the pump kicks on. Even when using the new variable flow water pumps, I think having a pressure tank is a good idea. ^.^d
any experiences with Seaflo pump? (http://www.foreforums.com/index.php?topic=28553.msg239886#msg239886)
The down side of a Hott Rod is that you no longer have a place for a sacrificial anode.
Atwood water heaters, due to unique tank construction, do not require a anode rod. See the Atwood Owner's Manual for specific guidance.
Atwood aluminum hot water tanks do not have the anode. They use a plastic drain plug that can be removed for the hot rod. But I would recommend that if anyone is changing their prpane hot water tank, and did not previously have 120-volt water heating, the new tank model have the 120-volt feature. No need for a Hot Rodd. That is what we did. It is the Surburban propane hot water tank that used an anode, because the tank is made of steel, not aluminum.
I didn't know about the cladding. The manual says it lasts longer than the anode rods that need changed annually, but doesn't give the cladding life.
The Atwood tank in our coach has lasted 23 years and still holds water...for what it's worth.
(Having said that, I'll probably go out to the coach today and find a big puddle of water on the ground below the water heater bay)
We put the Camco 10 gallon in our Atwood hot water heater and had a similar problem....installed the thermostat in a similar place as yours on the bottom of the tank and with the default 120F it blew the pressure relief valve so the water was more like 200F! though the heatgun said 140F in the puddle under the coach...definitly more than 120F. Water went everywhere! Think it is the same thermostat as used in the Hott Rod. Camco kit was good quality install and with the lit switch cost $78.00 on Amazon Prime. Anyhow, reset thermost to 90F (lowest setting) and it seems to be working...no pop off and not scalding hot water so far (5 hours)...will bump it up once i am confident the thermostat is working. Moral of story...after install stay with coach for a couple cycles to be sure it works so you dont fry the element and run your house pump on and on. BTW...run mine off an extension dropped under the bed thru the engine bay off the block heater switch outlet...not hard wired but easy to set up when we have shore power and can't drag down the inverter.
We ran a water hose from propane hot water tank temp-press relief valve down through floor so any drips or worse end up on the ground and not in the bay. When we flush the tank (about 3 x year), we open the valve to relieve pressure and let air in before we remove plastic drain plug (or Hott Rod) to flush tank. We put aluminum foil under drain to funnel drain to ground.
Another nice up grade is to change to either Girard or Attwood tank-less hot water heater, I install a few Girard's units they are only propane but they are very easy on propane, they only come on when hot water is being used, Plus unlimited hot water no need to wait for tank to heat up, They are not that much more then a standard Attwood water heater, and no cleaning out tank, Easy install no cutting .