Best place to splice into the cooling system

I'm installing an on-board hot water supply and hydronic cabin heater in the bed of my truck. I'm trying to determine where the best place to splice into the cooling system would be.

Locations I've considered are between the radiator and oil pump, or the exit side of the heater core. I know little about the cooling systems path of travel in the vehicle and these locations may not ever be feasible

Any thoughts or ideas?

 

why would you need a hydronic heater in a pickup? puttin on a camper and plan on sleeping in there many a freezing night? Is the hot water tap part of your heater system or for other uses? all sounds very risky to me. I would say whatever you do, make sure its at a location that is easily accessed, in case a leak were to spring.

 

Actually, that's exactly what I've been doing, all winter long. The heated cooling system is used to heat the cabin with the hydronic accessory heater and the water using a plate heat exchanger. I plan to install a diversion manifold in the engine bay to bypass the lines going to the bed... just in case.

 

Interesting system

 

I believe i know what your talking about here.

Best place would be after the heater bypass use a T or a Y fitting there and on the return use a T or a Y fitting just passed the heater also.

Imo dont splice into your rad hoses.

 

That was what I was leaning toward, a tee fitting on each side of the heater core with a ball valve on the side going to the bed on each. Anybody know where the two hoses pass though the firewall?

 

Ya, I'd tap in on the exit side of the stock heater core.
A bypass would be smart, but I would recommend leaving it open unless you have a problem or you could have corrosion issues from lack of flow.
The Suburbans with rear heat simply "tee" off and run the rear heater core in parallel with the front core.
They run steel lines to the bottom of the cab, then switch to rubber for the run along the frame and up into the rear heater core.

Bleeding air from the system is going to be a B*I*T*C*H if you don't include a purge valve at the highest point in the added system. Even if the rear core is lower than the highest point in the engine, flushing the air in the rear DOWN and out the exit hose is a major hassle.
Standard bleed procedure for a '95 Suburban is fill it, run it, fill it, run it, park it on a steep hill, and repeat.

 

Good point with the purge valve, hadn't even crossed my mind! Do you know if the Suburbans use a buster pump to circulate it all the way to the back? Or maybe just a big-ass water pump...

 

Just five point seven or more gas-guzzling litres

Seriously though, no... it was simply tapped into the front heater core circuit.
Basically the same thing for the rear AC... the compressor and condensor are the same, they just used different hoses that split off to the rear.
The rear evaporator had a thermal expansion valve to control the flow of R134, so when the rear fan was not on, the valve would "freeze" and shut flow off. Turning the rear fan on warmed the valve and allowed it to open, allowing R134 to flow until the valve froze up again.
Very primitive system and not very efficient, but it worked.
Rear seat had a separate temp control so if the people in the back seat got cold they could open the heater core diverter door and warm the air a bit (heater core was after the evaporator so the expansion valve still closed when it got cold).

 

That is primitive... also simple, and more importantly, hard to screw up. I'm yet to figure out the inner diameter of the line running in and out of the heater core? Seems like it has an outer diameter of 3/4 (rough estimate).

 

pleae please please lots of pictures all these major mods are of much interest to me

 

I'll follow up with pics as I get 'er done

 

5/8 return and 3/4 supply are typical for Chevy. I can't imagine Toyota running 1/2", but I don't know, and my Taco is an '08 so a measurement may not do you any good.

 

Is it normal to have a different size supply and return?

 

It's not uncommon.

And it makes for some fun times when you have a 5/8 and 3/4 on the stock core and an aftermarket unit that's 1/2 on both.