Scalding D5 Shower

[JJSporty]

We are hoping some of you might be able to offer advice on how to improve our SMB shower situation. We have a 2014 high-top SMB Sprinter 144 with a small shower compartment located behind the driver with a D5 on-demand water heater. It works well accept for the following annoying situation. Using the standard wet-down, soap-up, rinse-off short shower method, the water temperature fluctuation can be dramatic. I think this is due to the initial water temperature being set to a comfortable level with the two valves in the shower and then stopping the water flow at the shower head between wet-down and rinse-off while the upstream water is getting some extra heat from the D5 flat plate on-demand water heater while soaping-up. When the shower head valve is reopened the initial water flow is a bit cooler because the water in the plumbing has had a short time to cool a bit but when the water that was held in the D5 flat-plate makes its way to the shower head, it’s very hot, much hotter than the temperature the shower water was initially set for by using the hot and cold water valves in the shower. Has anyone experimented with adding a small hot water storage/temperature buffering tank or some type of recirculation circuit to improve this situation? We love our SMB and our shower but we’ve taken to using the shower compartment with a bucket of drawn water and a submersible shower pump to avoid the above described situation. We’d like to figure out if we can modify what we’ve got or at least design a better shower hot water delivery system for our next SMB.

[Wowbagger]

I have the same problem. What I've toyed with doing is just putting a valve from the hot line right at the shower, and running a line back to the fresh water tank. Crack the valve, and a trickle of hot would flow back into the tank, allowing a flow.

Failing that, I have thought about seeing if anybody makes a metering valve set in RV size connections.

[BroncoHauler]

For the deep archives of this forum, see this tread and maybe it will give you some ideas.

http://www.sportsmobileforum.com/for...alve-1313.html


Herb

[BVerhulst]

Herb, that's a good link. My SMB was built with a tempering valve at the flat-plate exchanger; JJ, I wonder why yours wasn't? Maybe on account of the D5 and the way it functions... I've never had one.

When I used to live in an RV, I'd set my water heater thermostat rather cool. Then, when showering, I'd use 100% hot water, no mixing, so the temperature remained comfortably consistent when taking water-saving showers. Don't know if that's an option you can employ with the D5.

[BVerhulst]

Oh, and mixing valves are sensitive to even mild freezing. Ask me how I know...

[Bbasso]

Can you heat the water in the tank to a temp you like and then shut off the heater?

[TomH]

Originally Posted by Bbasso

Can you heat the water in the tank to a temp you like and then shut off the heater?

It's a tankless (aka on demand) water heater. But I suppose if there were a recirculation valve you could heat all the water in the entire clean water tank, then pump it to the shower. Thing is, you wouldn't have any cold water and you might use more fuel than necessary.

[Bbasso]

Oh...
I didn't even realize that lol.