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Hose Sizes

7K views 9 replies 5 participants last post by  SteveSS 
#1 ·
Could somebody please give me the ID of these hose? I'm confused. I'd like to tee off of them for a water heater in back. Arrow 1 and 2 look the same and 3 looks a little larger, but I'm measuring OD, not ID.



TIA,
Eric
 
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#2 ·
I put my Tees in both hoses at your point 3.

Poster wbullivant said the factory Tees he got with the rear heat option were 3/4 x 3/8 x 3/4. With the 3/8 going to the rear heater.

The factory parts aren't available, at least not at my dealer.

I bought some plastic heater Tees at Napa that said they were for Fords.

They worked pretty well, but they were always weeping a little and I would have to retighten them frequently.

After about a year they deformed and the 3/8 hose barb broke off while we were visiting a car show in Amelia Island, Fl. But that's another story that involves a very nice salesman at a Dodge dealer in Georgia, 2 partial gallons of coolant from the closed service department for free and being driven to 2 auto parts stores by the salesman on a Sunday to buy replacement Tees.

After returning home I bought different Tees from Napa that were much higher quality. They came from a plastic box in the back of the store with various sizes of Tees, ells and straight connectors and like they looked like they were possibly glass filled plastic with a nice sharp barb.

I bought 2 each of both 3/4 x 3/8 x 3/4 and 5/8 x 3/8 x 5/8 just in case. I installed the 3/4 ones but still had the weeping at one joint. So I replaced one of the 3/4 Tees with a 5/8 Tee. I believe it was the hose closest to the firewall, but can't remember. The weeping stopped.

I used what I believe are called constant tension hose clamps. Or something like that. They have slots like a normal gear clamp but the inside is a separate smooth stainless band that spreads the tension equally around the hose and with no slots, it doesn't dig into the hose when tightened.

Maybe the hoses are a metric size. But I haven't had any coolant loss in 3 months using the 3/4 size in one hose and the 5/8 size in the other.

Maybe wbullivant will post with his experience with the factory parts. Or search for his post with pictures of the parts. He and I both installed ball valves in the 3/8 hoses going to the water heater to isolate the system in case of a leak. Unfortunately my leak was in the Tee.

wbullivant said he drained his cooling system before installing the Tees. I asked the service manage at my dealer how he would do it and he said to just cut the hoses, insert the Tees and replenish whatever small amount leaked out. I did it that way and it didn't take more than a pint or so to refill.
 
#3 · (Edited)
The 3/4 to 5/8 swap you did makes sense as the hose closest to the firewall does look slightly smaller at position 3. I'm going to try to find brass parts now that I know what to look for and clamps like you suggested.

For valves, I'm thinking of installing 12v solenoid or 12v motor actuated valves, I not sure which, so I can open or close them from the cab. I'm not keen on running very hot coolant through the water heater for the hours I drive to get to where I'm going. Ebay has either one for not much more than plain ball valves. Maybe I'm just paranoid.

Thanks, again.
 
#4 ·
I couldn't find metal ones and the higher quality plastic ones that I got from Napa are quite good. They just didn't have them in stock the first time I went.

I used them in a previous camper I built on a 4 x 4 Mitsubishi Fuso for the same purpose. They were still fine after 10 years when I sold it and I suspect they are still okay now (3 years later).

That fitting in your picture of the larger hose is plastic.

I just pointed out the trouble I had with the cheaper version that I bought the first time.

Attached is a picture of what the good fittings look like. Some came from a box with assorted sizes and some came in a bag marked Gates Rubber. The clamp is the type I mentioned and the box said Napa Balkamp and the description says 'lined'.

Whether you run hot coolant through the heater on long drives is up to you.

I used a marine hot water heater made by Webasto Isotherm in this and the previous camper and I believe they are made to run continuously with engine coolant running through them.

I used silicone heater hose that runs under my promaster until it reaches just in front of the rear axle before it enters the van where the water heater is located. I have foam pipe insulation from home depot over the heater hose just to prevent heat loss in the winter and keep some heat out of the van.

In the previous Mitsubishi camper I would sometimes close the valve manually during the summer and open it a half an hour or so before stopping for the day and the water would be plenty hot that night and the next morning.

The Isotherm heater has an adjustable thermostatic mixing valve that mixes in cold water from the inlet with the hot water coming from the tank to maintain a lower temperature because the water in the heater will reach engine temperature of 190 -210 F.

And they recommend a single lever mixing faucet at the sinks and shower to adjust the water temperature to prevent scalding.

What kind of hot water heater are you using in your Promaster?
 

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#6 ·
My water heater is a 4 gallon Atwood marine type that runs on 120v or circulating hot water. The 120v is hooked up but not always convenient. I intend to put the Isotherm mixing valve on this heater. Isotherm sells this as a retrofit kit.

The solenoid or motor driven valves are just a geeky option I'm thinking about. The lady at Atwood said there was no problem running hot coolant through the lines continuously so I may just use ball valves. I just thought an hour before I reach camp I could throw a switch and heat up my water. They're less than $20 each on eBay or Amazon; not much more than ball valves, which is actually kinda scary.


I'll be using the silicone hose also, but ****, that stuff is expensive.

Thanks again for your help.
 
#10 ·
If you are adding ball valves at the engine end (good idea), you won't need reducer tees. You can just use tees that are 3/4 (or 5/8) all round, since you can do your reducing at the valves by screwing different sized barbed nipples on each end of the ball valves. Amazon.com has lots of barbed brass tees and nipple fittings.

And yes, one valve is enough to control coolant flow, if placed on the supply-side hose (#2 in your photo). That's how dash heaters are controlled. The #1 hose with the 90-degree bleeder valve attached is the coolant return hose. However, valves on both hoses, at both ends, (4 total) gives you the most flexibility for reducing coolant loss when servicing hoses, water heater, etc.
 
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