XPAG plumbing for heater

[Tom Wilson]

I would like some input on plumbing for a heater connection to an XPAG engine.
Hot water source will be tapped from the water outlet - the piece attached to the front of the cylinder head that the thermostat sits on.
Water flow needs to be maximized - in the proper direction - to the heater from this source, then returned to an optimum return point.
I've seen many setups for this, and have learned that several suffer from inadequate coolant flow to the heater.

So the 2 questions are:
1. What keeps the coolant moving the right way and in sufficient quantity through the heater system?
2. Is there a best point of return for the coolant from the heater to maximize the flow of coolant?

All smiles, jokes, satire, and real answers are welcome!
Tom Wilson

[Gene Gillam]

Tom,

Here's one way it's done: http://www.ttalk.info/LawsonHeater.htm
More info here: http://www2.mgcars.org.uk/cgi-bin/gen5? ... 0161311903

Flow info here: http://www.ttalk.info/XPAGCooling.htm

[stephen stierman]

Tom,
Mine is set up with a small pipe from the branch or Y pipe between the water pump and lower radiator outlet with a hose running below the carbs, through the firewall to the heater. The return hose comes off the heater, through the firewall to an outlet on the cover plate at the rear of the cylinder head. There is shut off valve located adjacent to the heater unit in the interior plumbed into this hose. I am not sure of the direction all this flows or what the most efficient set up is. I will say that my top and curtains fit pretty snugly and the heater unit located above the gearbox tunnel seems to put out more than adequate heat for this sort of vehicle.

[Eric Worpe]

Hi Tom,
Just a thought to consider, how well would it work if the by-pass hose between thermostat housing and the outlet at the bottom of the radiator was substituted by the heater. You would certainly receive the initial hot water output of the engine and in cold weather not all the hot water is directed through the radiator, as it would be cooled too much. The back of the cylinder head is relatively cool as the cooler water from the radiator flows along the manifold on the side of the block to the back of the block and then up to the back of the cylinder head.

[John Seim]

Tom, Ben Cordsen makes the adapter that goes in the by-pass hose. There is on ebay an Arnolt MG brochure, that shows the plumbing of their heater. Shows the adapter that Ben makes. 1/2 inch copper pipe, and rubber hose, along with some copper street elbows, and a little soldering, can make a nice installation. Nostalgic Air Parts sells a manual shut-off valve.

[Rick Waters]

I've seen a TC with a well-functioning heater. On that car, the hot water feed for the heater came from the front, bypass hose, I believe, and the return hose went into a fitting that was installed on the rear of the head, in the rectangular plate that is attached by four screws.

[stephen stierman]

yes, essentially that is the way mine is set up, I laugh at the weather..........

[Eric Worpe]

The cool outlet of the radiator is coupled directly to the pump's input, the pump's output then flows directly to the back of the cylinder head where it is then distributed around the water ways. If one heater connection is taken from the radiator's cool outlet and the other heater connection is made to the back of the cylinder head, the heater is not in the hottest part of the loop and is also placed in parallel with the pump. I'm not sure this is the most efficient connection and it would also reduce the flow rate through the engine block.
Substituting the by-pass hose for the heater seems to have some merit if the skirted thermostat is used.

[John R McNarry]

I used Ben Cordsen's bypass method. The bypass tube is replaced by a short length of copper tube with a blanking disk soldered in the middle. Two 1/2" copper elbows are soldered to the tube one above and one below the blanking disc. I placed a 1/4 turn lever operated ball valve just inside the firewall and connected it to a control rod that I can easily reach beside the heater. This system works very well. I never have had overheating issues or warm up issues even with the ball valve closed.