| Author |
Message |
doug yes (Dougg)
Registered Member
Username: Dougg
Post Number: 23
Registered: 1-2007
Posted From: 75.89.18.67
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 26, 2007 - 7:47 pm: | |
We're installing a pancake shaped heat exchanger to get hot shower water off the engine. Question: Do we need to install a pressure/temperature release valve in the pottable water line somewhere? And will we be getting overly hot water, close to engine temperature? |
Jerry Liebler (Jerry_liebler)
Registered Member
Username: Jerry_liebler
Post Number: 245
Registered: 3-2005
Posted From: 67.141.40.68
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 26, 2007 - 9:05 pm: | |
The answer to your actual question is probably no, because your engine coolant temp will always be below boiling. BUT!! Be a bit carefull here! You'll get very sick or worse if that heat exchanger develops a leak and you end up making coffee with hot water contaminated by antifreeze. There are what are called double wall heat exchangers that are quite safe against this problem but they are far less common and significantly more expensive. Another alternative is two cascaded heat exchangers with the 'loop' between them filled with nontoxic antifreeze, the RV stuff or swiming pool antifreeze both of which contain propylene glycol which is non toxic.
Regards
Jerry 4107 1120 |
Robert Cox (Bob05)
Registered Member
Username: Bob05
Post Number: 5
Registered: 5-2007
Posted From: 75.14.223.10
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 26, 2007 - 10:01 pm: | |
Doug be very carfull with that ok, I 'm runnung a setup made by Webasto and a seaward hot water heater that the system is all self conatined. pump on the webasto takes the engine heat through the system heating water heater which is also an electric water heater. |
John MC9 (John_mc9)
Registered Member
Username: John_mc9
Post Number: 336
Registered: 7-2006
Posted From: 66.217.105.196
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 26, 2007 - 11:49 pm: | |
Any normal hot water heater (rv or household) can accommodate
a coil of 1/2" copper tubing wrapped around the outside of the tank
(inside the housing). The ends of the copper tubing can be fitted
nicely to lines running to/from the engine radiators or water pump.
Cheap, easy, no contamination, and it works.
Oh.... and
<i>"Question: Do we need to install a pressure/temperature
release valve in the pottable water line somewhere? And will
we be getting overly hot water, close to engine temperature?"</i>
There should be a pressure relief valve on the water heater,
and that's all that's usually necessary. The water temperature
will be mixed with the cold at the sink or shower, right?
(Message edited by john_mc9 on May 26, 2007) |
Len Silva (Lsilva)
Registered Member
Username: Lsilva
Post Number: 119
Registered: 12-2000
Posted From: 71.30.242.232
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 27, 2007 - 9:25 am: | |
In addition to the temp/pressure valve I would STRONGLY advise everyone to install an automatic temperature valve in the shower. My Motor-Aid heater can get quite hot after a trip and the shower can get dangerously hot if someone turns on a cold water faucet. I will install a new shower valve very soon.
Len |
John MC9 (John_mc9)
Registered Member
Username: John_mc9
Post Number: 337
Registered: 7-2006
Posted From: 66.217.106.104
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 27, 2007 - 11:14 am: | |
The high-priced temperature control we added to our motorhome's
shower never worked when using the system's water pump. It seemed
the pump's pulses confused the control's workings.....
Just something to keep in mind before stepping into the shower... |
Nick Badame Refrigeration Co. (Dnick85)
Registered Member
Username: Dnick85
Post Number: 113
Registered: 2-2006
Posted From: 75.196.111.101
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 27, 2007 - 8:30 pm: | |
Hi John,
Great idea!
You can go to your local plumbing supply house and purchace a "H2O mixing valve" for about 40 bucks. We use theese on home boilers that have domestic heat exchangers. I also installed one in my bus. I have a 12gal electric H2O That I have turned up to 150 deg. then I mix it back down to 115 deg. with cold water. It increases my 12 gal cap. to roughly 17 gals...Longer Showers!!
Nick- |
George M. Todd (George_mc6)
Registered Member
Username: George_mc6
Post Number: 168
Registered: 8-2006
Posted From: 207.231.81.59
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 28, 2007 - 12:33 am: | |
Nick is right! Some of the plumbing houses will call it a tempering valve. I am puzzled by John's comment about pulses confusing his shower's tempering valve, and don't know whether or not the same thing would happen with one of these Watts valves? Definitely worth a try.
If this valve confuses you, ask, either Nick or me will be glad to explain. (Christy can explain one well also!)
HTH, George |
Tom Caffrey (Pvcces)
Registered Member
Username: Pvcces
Post Number: 1093
Registered: 5-2001
Posted From: 65.74.65.197
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 28, 2007 - 3:52 pm: | |
I don't know about you guys, but I have seen a heck of a variation in the performance of tempering valves. They spook me a bit.
I know of one apartment house that relied on one for years and it performed very well. In another case, the water temperature went up and down all the time.
I don't know how they are designed, so my ignorance is showing, but when they work well, they are nice to have.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska |
George M. Todd (George_mc6)
Registered Member
Username: George_mc6
Post Number: 172
Registered: 8-2006
Posted From: 207.231.81.59
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 28, 2007 - 9:41 pm: | |
A question Tom?
Could the fluctuation be the result of low hot water supply? Tempering valves are good, but they can't make hot water. Also, the second place could have had a plumbing error, which didn't supply enough cold water to the water heater to push the hot water out?
FWIW, George |
Nick Badame Refrigeration Co. (Dnick85)
Registered Member
Username: Dnick85
Post Number: 114
Registered: 2-2006
Posted From: 75.196.173.114
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 29, 2007 - 1:05 am: | |
Hi Tom,
A few years back, one of my guys installed a mixing valve backwards and the result was what you discribe. Hot, cold, then warm...It took a little thinking to correct that one....
Nick- |
Donn Reeves (Donnreeves)
Registered Member
Username: Donnreeves
Post Number: 2
Registered: 3-2007
Posted From: 69.115.76.219
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 29, 2007 - 7:28 am: | |
As I understand your plan, the drawback would be that the engine would have to be running to have hot water.Unless you add a storage tank with a ciculator pump.I don't see that a TP valve would be nessisary. I'm using a flat plate heat excanger that is 10"x6"x2" to preheat the water going into my 11 gal Seward hot water heater.It gives a 30-40 degree heat rise hooked up to the Pro-heat running at 175 degrees. |
Tom Caffrey (Pvcces)
Registered Member
Username: Pvcces
Post Number: 1096
Registered: 5-2001
Posted From: 65.74.65.197
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 30, 2007 - 1:30 am: | |
Thanks for the ideas. You guys have given me some things to watch out for.
Tom Caffrey PD4106-2576
Suncatcher
Ketchikan, Alaska |