Rear Seat Heater Return Line

[psea17]

Hey guys!

Hope all is well. Im embarking on a little project to install a hest exchanger plumbed into the return line of the rear seat heater. I plan to use it to warm water for showering. Used AI (coming clean; hard to admit it wasnt my idea) and learned that plimbing into the return line allows me ti use the rear thermostat control to adjust water temp. Kind of cool if it works. FYI, i had to use A LOT of prompts to get the info as it originally told me i could do the same thing plumbing it into the send line (vs the return line). It finally responded, "Good catch" when i noted installing it before the heater woild defeat rhe purpose of ising the heater thermostat. Lesson being, it's not quite fool proof yet. Anyway, i digress.

I asked it which line was the return line and it said the the hard line outboard is the return line. Due to the above experience, i just wanted to confirm it w/ the T4R brain trust.

Ive attached a pic of what i believe are the 2 connections in the loop where the tubing meets the hard line and have marked on the pic which one i believe to be the return line.

Can someone confirm?

The last challenge is where to install it. It's approximately 3"x8" and most likely must be installed vertically to address any air caught in the system. Right now the leading location is actually against the battery. I plan to insulate the battery w/ 1/2"-1" rubber w/ an adhesive backing and then use two webbing straps wrapped around both to keep it well secured. Then it's easy to remove if i need to pull the (brand new) battery for whatever reason.

Anyway, that's the plan. Just looking for return line confitmation.

THANKS!

 

[alumarine]

I can't confirm the return line but if you run the rear heater and adjust the temperature control the cooler of the two lines should be the return.
An I/R gun would make it easier.

 

[psea17]

For others looking for the same info....

With the hood open, facing the firewall, on your heater control valve (HCV), there's an arrow pointing to the passenger side. This is the flow of coolant. Prior to reaching the HCV, it branches off to the lower sitting hard line to the rear heat seater. This is the inlet to the rear heater. That means the one sitting higher (closer to the passenger side) is the outlet.

Hope that helps.

PS. I don't have a laser thermal temperature tool, so they both felt the same w/ the rear heater set to the minimum. Once I turned it to full heat, i believe there was a slight diff in temp between the inlet and outlet. Makes sense there'd be less heat w/ the heater on full blast....cuz, well, the heater is taking the heat (vs when it's set to the coolest temp).

So, for my shower set up, the cooler i set the heater, the more heat I should expect to flow through the heat exchanger.

ps2. After scouring YT looking at videos, seems quite a few installed it horizontally against the firewall. Apparently it didn't result in any airlock issues. This was my preferred installation location. I'm going to install there.

THANKS for the response.

 

[phattyduck]

So, for my shower set up, the cooler i set the heater, the more heat I should expect to flow through the heat exchanger.

I'm not 100% sure on this, but I believe the rear heater is a 'full flow' design - there is no valve for the rear core, just a blend door. You can prove this by checking if the lines get hot with the temp set to full cold/off.

Do you use the rear heater at all? I turn it on to check function maybe once a year... Maybe you can just bypass the rear heater and run the lines 'full time' to your heater exchanger.

-Charlie

 

[psea17]

i never use the rear seat heater. that's the reason i wanted to try this. hoping the thermostat/blending has some temp control. if not, i can just cycle the water into a bucket until it's a comfortable temp.

ive assmbled all the parts. just need to mount. will post a pic when done..

appreciate the response!