I have a question regarding hot water heater capacity. I currently have two RV's, one with a Suburban propane manual start 6 gallon and the second with a Suburban propane 6 gallon with direct start ignition. The RV with the manual start hot water heater works great and provides enough hot water capacity for a regular shower. The RV with the direct start ignition unit might provide 3min of a hot shower before going cold. I recently bought the second RV because it had some upgrades like this water heater but it doesn't work nearly as good as the older manual start unit. The model of the DSI unit is a Suburban SW16D. The manual says the thermostat is non-adjustable. I also have a friend with the exact same RV and hot water heater except he doesn't have any issues.
Any ideas what what might be reducing the capacity of the DSI hot water heater?
I would guess the water is getting hotter in the hi cap heater, could be due to a defective thermostat in the lower capacity one.
Also 1 tank could have a gallon of crud in the bottom making for less capacity
Rich
'01 31 ft Rexall Vision, Generac 5.5k, 9245 conv, 400 watt inv, 2 12v batts, ammeters, KingDome/sat, Two Oly Cat heaters, and towing a '05 Jeep Liberty, or sometimes towing a Lowe bass boat.
Is it possible that the shower head in the one that runs out of hot water has a different or higher flow shower head? You can find out by using a bucket and a stop watch. Turn the shower on full and then after ir is flowing, aim it into the bucket and start the stop watch. After one minute, take the shower head out of the bucket and then measure the amount of water in the bucket. That will give you the Gallons per minutes. Do this for each RV and compare the flow for each RV. you might find the problem. My solution to the problem is an "Oxygenics" shower head. It gives a good feeling shower and only uses 1 1/2 GPM at full flow, so 6 gallons of hot mixed with a flow of cold to temper should give you at least 8 minutes of useable warm shower. Also you might want to check to see if this heater has a By pass valve and that it is indeed open wide.
Othertonka
2004 Southwind 32VS 8.1 Workhorse chassis
2002 CRV Toad
U. S. Gear Unified brake system
Retired Fire Captain, SFD
Some people have mentioned having problems where the hot water is being mixed with the cold water. Places where you might check the pipes are outside showers and the valves you change when you winterize.
Also test the the hot water at the kitchen sink and see if it also runs out in only 3 minutes.
RJsfishin wrote: I would guess the water is getting hotter in the hi cap heater, could be due to a defective thermostat in the lower capacity one.
Also 1 tank could have a gallon of crud in the bottom making for less capacity
Hi Rich. Both units are the exact same size so I don't think that's the issue. I will pull the tank plug and drain any sediment. The thermostat sounds more likely but there is no user adjustment available. Maybe it's defective or is installed incorrectly.
Clean the tank and check the bypass valve. Check the outside
shower valves and make sure the tank is filling all the way up.
Could have some air in it. Look at the flame and make sure its
blue.
Hope this helps
Thanks everyone for the advice. I'll run through the tests mentioned above and see what I can determine. I noticed nobody mentioned the internal thermostat or thermocouple as possible problem areas. Is that because they probably aren't causing my issue?
I also suggest checking to see if the kitchen fauscet is also cold once the shower water is cold, to see if it is a local or system problem.
The cold water is supposed to enter the bottom of the hot water tank, and slowly rise up to the top, pushing out the 140F water as it goes, not mixing the incoming 50F water with the 140F water and creating 90F water after a really short time.
I think that you might have a problem with the fill tube, not going all the way to the bottom of the tank anymore, so the cold incoming water is making it's way to the output line to soon.
My guess is that you are running the heater on gas the whole time you take a shower? I guess I would get rid of my RV if I could only take a 3 minute shower too!
Try draining the sedimate first, then start looking at the cold water mixing with the hot, if the kitchen sink is as cold as the shower water.
If the kitchen sink still has hot water, while the bathroom is cold, then consider a outside shower fixture might have been left turned on at the hot and cold valves, with the shower portion turned off, allowing water to flow backwards in that fixture. Or there might be a problem with the winterizing bypass valve, or something else in the RV piping causing the water to turn lukewarm after a short time.
If you open the water heater compartment door, the thermostats will be exposed to slightly cooler air, and this might cause the burner to run a little longer, warming the hot water a bit more (perhaps 10F warmer hot water). It might be worth a try, no cost anyway.
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