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Old 08-07-2016, 05:33 PM   #41
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No problem JR. Since the only time you want water going back to the main tank is while you are waiting for the heater to make it hot, once the water is hot you can chose to shut off the flow back into the tank via the solenoid valve. The water pump which supplies the heater is all you need . It pumps water through the heater, to (or past) the spigots and back into the tank (if the valve is open).

From the practical side I use a separate pump for hot and cold water because the Ecotemps are fussy about both pressure and flow rate. I generally leave the solenoid valve open the whole time I am using hot water as the 3 gpm pump Ecotemp recommends easily supplies the spigots and return line as well. I found this practice also helps stabilize the water temperature at the spigot because the heater isn't cycling on and off.

I have a 60 gal water tank and the returning hot water begins to show itself in the temp of the fresh water when Its down to about ten gallons. Since the Ecotemp heater is capable of heating incoming water 30-35 Degrees F above ambient, the heated stored water can set up a scenario where the heated water gets hotter and hotter to the point in my case where the PVC pipes swelled and a joint failed. I solved this problem by installing a programmable thermostatic switch to sense the temp of the water comming out of the heater and to shut off the burner when exiting water temps reached 109 degrees F. That solved the problem. I have several of these controllers in use and they work great--less than $10. Jack

Digital MH1210A 12V 10A All Purpose Temperature Controller Thermostat Sensor New | eBay.

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Old 08-07-2016, 07:38 PM   #42
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Quote:
Originally Posted by Jolly Roger View Post
Ok are all of you talking about your hot water return going to your fresh water tank?
It looks like it by the schematics? It will work great for the hot water storage and hot water supply but you won't get any cold water.
The diagrams shown show no dedicated hot water return line or dedicated pump?
Is my commercial experience making me stupid to what y'all are proposing?
A hot water return system has a pump that draws (regardless of placement after/from)the farthest fixture away from the heater and dumps into the cold water inlet of the water heater which tempers the cold water into the heater. Whatever it is?
Sorry jack? I ain't understanding the valve placement or its purpose without a pump to circulate the hot water itself back to the heater/storage tank?
Please help me understand the idea
seems the concept needs to be a 'DHW' loop... a little pump that is turned on cicrulating hot water from the furthest device back to the inlet of the HEATER.. NOT the fresh tank.. and that also gives the water heater some "ballast" for starting up and shutting down and not under or over-temping...

-Christopher
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Old 08-07-2016, 09:24 PM   #43
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There are probably ten ways to design a skoolie hot water system. I like the idea of the small pump but as you describe it, it would lead to no circulation just as soon as the main pump kicked in and overpowered the little pump. I suppose it might work if the return line fed the pump inlet although the continual increase in water heater output temp due to recirculating hot water would still need a true thermostat to maintain a constant temp. RV water pumps don't allow back flow so the 'Ballast" idea becomes irrelevant.

I've shared my experiences both good and bad on this topic and hope they have been of some help.

I remember a slogan from when I was a kid in the early 1950's "When better cars are built, Buick will build them"--I'm still waiting. I guess that holds true for a lot of things. Jack
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Old 04-22-2017, 03:07 PM   #44
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I was glad to find this post with the plumbing design and all the helpful information. This is going to be my first build and I am really grateful to have found this site.
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Old 04-24-2017, 05:38 PM   #45
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I have a similar design, with some slight twists:

1) the temperature control is a single button. press to call for hot water preheat, a blue light illuminates until the temp is brought up, and it turns to red. If you don't press the button any more, or stop using the fixture, the timer circuit deactivates after about 2-3 minutes. The temperature controller activates a solenoid dump.

2) I have 3 lines going to each fixture, and two 50 gallon fresh tanks. They're equalized at the bottom with a 3/4" line, but hot draws from one tank and cold draws from the other tank. The hot returns dump back into the hot tank.

3) I avoided using pvc, so just pex, brass and copper lines. We are using a
girard gswh-2 heater, I don't know what it will think if it's water supply temp is already 70 deg f, but I'm guessing it might just throttle back the output or set an overtemp alarm.

Also, that heater has a cold protection mode that activates the burner for short periods of time when the temp is below 38F, so that's neat. I may use one or more of the hot return lines to do the same thing in the equipment bay, making a discount radiator heater.


Quote:
Originally Posted by ol trunt View Post
No problem JR. Since the only time you want water going back to the main tank is while you are waiting for the heater to make it hot, once the water is hot you can chose to shut off the flow back into the tank via the solenoid valve. The water pump which supplies the heater is all you need . It pumps water through the heater, to (or past) the spigots and back into the tank (if the valve is open).

From the practical side I use a separate pump for hot and cold water because the Ecotemps are fussy about both pressure and flow rate. I generally leave the solenoid valve open the whole time I am using hot water as the 3 gpm pump Ecotemp recommends easily supplies the spigots and return line as well. I found this practice also helps stabilize the water temperature at the spigot because the heater isn't cycling on and off.

I have a 60 gal water tank and the returning hot water begins to show itself in the temp of the fresh water when Its down to about ten gallons. Since the Ecotemp heater is capable of heating incoming water 30-35 Degrees F above ambient, the heated stored water can set up a scenario where the heated water gets hotter and hotter to the point in my case where the PVC pipes swelled and a joint failed. I solved this problem by installing a programmable thermostatic switch to sense the temp of the water comming out of the heater and to shut off the burner when exiting water temps reached 109 degrees F. That solved the problem. I have several of these controllers in use and they work great--less than $10. Jack

Digital MH1210A 12V 10A All Purpose Temperature Controller Thermostat Sensor New | eBay.
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