Go Back   iRV2 Forums > MOTORHOME FORUMS > MH-General Discussions & Problems
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 01-11-2010, 05:39 PM   #1
Senior Member
Join Date: May 2007
Posts: 146
Mixing Valve in Water Heater

We have an Atwood Water Heater and recently have noted that our hot water is warm at the tap (100 to 104 degrees) but at the heater it is 135 to 140 degrees. This leads us to believe that...once again...the mixing valve has failed. Today we took the MH in for service on the water heater. First of all, the technicians claimed we didn't have a mixing valve on it. At which point, we said..."oh yes we do...and here is the previous service order where it was replaced". Shocked as they were, they did look and sure enough there was the valve. They have suggested that we bypass...or remove entirely...the valve. However, we note that it will void the warrantee on the water heater. Have any of you done that? If so, how and have you had good results?

David and Fran
Airstream Classic
David and Fran is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 01-11-2010, 05:50 PM   #2
Senior Member
Jim Stewart's Avatar
Monaco Owners Club
Join Date: Nov 2008
Location: Melbourne & Marathon, Florida
Posts: 1,537
The Atwood heater that has a mixing valve is supposed to do what you describe. A conventional 10 gallon heater gives you 10 gallons of hot water, The XT is supposed to heat the water hotter than a normal heater and then through the mixing valve, mix it with colder water to deliver a total of 16 gallons of hot water.

It seems it is working correctly, the problem may be that the temperature is set too low at the tank and when you mix the 10 gallons of hot (140 degrees) with 6 gallons of cold (ambient, 40-60 degrees or less depending on where you are in the USA today), you go from 140 down to about a 104 degrees.

Is there an adjustment to increase the temp at the tank and/or an adjustment on the mixing valve to allow a greater percentage of the hot verses the cold for the mix?

2005 Safari Cheetah 38PDQ - 2009 Ford Flex
Me (Gatogonow), The Boss (DW), Honey Bunny, Maggie May and Mollie Kay (The Gatos)!
Jim Stewart is offline   Reply With Quote
Old 01-11-2010, 05:57 PM   #3
Administrator in Memoriam
Route 66's Avatar

Newmar Owners Club
Retired Fire Service RVer's
Spartan Chassis
Join Date: May 2000
Location: Newark, DE
Posts: 25,909
As Jim notes, removing the valve will reduce your hot water capacity and deliver dangerously hot water.

I'd replace it.
Adios, Dirk - '84 Real Lite Truck Camper, '86 Wilderness Cimarron TT, previously 4 years as a fulltimer in a '07 DSDP

Route 66 is offline   Reply With Quote
Old 01-12-2010, 02:56 AM   #4
Community Moderator
RV Wizard's Avatar

Country Coach Owners Club
Appalachian Campers
Gulf Streamers Club
Join Date: Mar 2000
Location: Chattanooga, Tn.
Posts: 12,062
It has been found and is required maintenance to remove, soak the valve assembly in hot white vinegar to remove mineral deposits that hinder it from working properly. Unless you have a water softener ahead of the water inlet you will probably have to do this when the water does not seem to be as hot as before.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7
RV Wizard is offline   Reply With Quote
Old 01-12-2010, 04:54 AM   #5
Senior Member
paz's Avatar
Join Date: May 2005
Location: Full-timers - Home is where we park it.
Posts: 4,716
I assume the thermostat in the Atwood water heater is fixed and can't be adjusted for temperature, and removing the mixing valve would result in dangerously hot water as Dirk says.

If you get tired of replacing and/or soaking the mixing valve and wanted to remove it completely, would it be possible to replace the 140 degree thermostat with a standard one? That way the temperature wouldn't be dangerously hot, although you would have less volume of hot water. We get along fine with 2 people and a washer/dryer with a standard 10 gal. water heater. We just allow 15 to 30 minutes between showers, and the water is plenty hot. Oh yeah...make sure you don't start the washer just as someone steps into the shower either.
2015 DRV Tradition 375KPS
2015 Chevy Duramax 3500HD LTZ Dually
Full-timers...Home is where we park it.
Check out our blog: Living Our Dream
paz is offline   Reply With Quote
Old 01-12-2010, 05:27 AM   #6
Senior Member
Avalondanes's Avatar
Fleetwood Owners Club
Join Date: Jul 2007
Location: Salisbury,North Carolina
Posts: 229
As posted, do not by-pass the mixing valve. You will have water that is way too hot. The mixing valve has a red or black plastic "knob" on it. In the center is a allen head screw, remove the screw then pull the "knob" off. This gives access to the temp adjusting screw. Adjust this to give more"mixed hot water" at your faucet then install the "knob".

2006 Revolution 40L, 400HP Cat C9, Allison 6 speed, Spartan Chassis, Aero-Turbine Muffler
Avalondanes is offline   Reply With Quote
Old 01-12-2010, 02:42 PM   #7
Senior Member
Join Date: May 2007
Posts: 146
Thank you all! We have a mixing valve kit on order and will have it installed when it arrives. I did speak with Atwood Customer service and they verified almost everything you have advised. Their only comment was that we shouldn't try to adjust the mixing valve as Richard suggested. We were happy when it was working properly...and will be again tomorrow!! They did send me a "new" owner's manual which states that the tank should be flushed every 60 days for full-timers or every 30 days in the SW USA and for part-timers twice a year or every 90 days if in the SW USA. They also suggest using the solution described for ridding the tank of unpleasant odors annually to clean the tank of any accumulated scale deposits. By the way, we'll do a water softener too!

David and Fran
Airstream Classic
David and Fran is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Found o-ring that works for "HOT" side water heater check valve. RTZ6885 Winnebago Industries Owner's Forum 1 07-13-2008 11:09 AM
Propane too 'rich' @ hot water heater glfprncs MH-General Discussions & Problems 7 02-27-2007 09:06 AM
water heater bypass confusion ottersea Winnebago Industries Owner's Forum 2 10-13-2005 07:00 AM
Hot Water Heater Release Valve rhandley 5th Wheel Discussion 3 10-04-2005 04:47 PM
Hot Water Heater valve retired_ranger RV Systems & Appliances 2 10-01-2005 02:46 PM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 06:32 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.