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MG TD TF 1500 - Installing Smith's Round Heater

Installing Smith’s Round Heater
I’ve been given a Smith’s round heater (see picture of the back of the heater attached) for my ’53 TD (25004). I plan on routing the hot water out of the back of the head by brazing a fitting into the rear head cover plate (Moss 290-800) and through the firewall using a Triumph TR-4 connection (Moss 635-220). I will route the return into a T fitting in the hose between the branch pipe and the thermostat housing elbow. Hopefully, all of that will be fairly straight forward.

Where I’m puzzled is how to mount the heater under the dash. There is an L bracket that appears to be welded to the center of the underside of the battery box. I don’t know if this is original or something added by the PO but it seems suitable for the top stud on the back of the heater. I’m thinking that I can bolt a pair of angle braces to the underside of the battery box to accept the two other studs. I’ll mount the rheostat control to the back of the sub-dash.

I’m flying blind here so any and all suggestions before I start drilling holes in the bottom of the battery box and through the firewall will be greatly appreciated. Thanks. Jud

ps: After typing but before posting this I did a Yahoo search and found 2009 thread
http://www.mg-cars.net/mgtd-mgtf1500-bbs/heater-installation-2009122200465526816.htm
And this 2014 thread
http://www.mg-cars.info/mgtd-mgtf1500-bbs/td-heater-system-201410230130571625.htm

These have some great ideas and answer many of my questions. Attaching a mounting board to the cross bar behind the dash sounds like a good way to go but other suggestions are still invited.



J. K. Chapin

The front with the door open.


J. K. Chapin

I'm a bit worried about your plumbing---
Both spots you have mentioned are hot water outlets and you won't get any ,or much circulation
You could use either of these as your hot supply but the return has to go back into the waterpump inlet (bottom hose)
The fitting in the plate at the rear of the head is possibly the easiest hot water supply but the hottest water will be from the front housing just below the thermostat (not above)

So best setup is from that front fitting below the t/stat --through the heater and back to the inlet of the pump
William Revit

Thanks. I'm still trying to get my head around how the water actually flows. I know that the rear plate is not the hottest but I live and drive in South Carolina so I don't need the hottest. I think I understand what you are saying about the return into the bottom hose and will take a look at how to do that tomorrow.

I've attached an annotated pic of the branch pipe and it's hoses. Is hose 3 a suitable return place? Are any of these suitable for the return? Am I in the right area for the return?

Should I just braise an outlet into the branch pipe itself?

Thanks.

Jud



J. K. Chapin

Jud,
I mounted Smiths heater with eye bolts so that I can swing it aside by loosening the bolts so I can access the gearbox filler cap. I replaced the original motor with a high efficiency computer fan motor which only draws 0.45Amps.
Regards
Declan


Declan Burns

Rear view showing funnel to deflect the heat radially. The cold air is drawn in from the front and over the motor and deflected radially via the funnel. My heater had no doors.


Declan Burns

The heater is mounted via exhaust clamps 40mmm and DIY brackets under the scuttle.
See drawing. If you need a higher resolution send me a PM.

Regards
Declan


Declan Burns

This is the control valve I used. I tapped the hot water from the thermostat elbow.

Regards
Declan


Declan Burns

You can just about see the control valve behind the back of the rocker cover.
Regards
Declan


Declan Burns

My Smith heater. PJ



PJ Jennings

This is what how mine is mounted. 1/8" Plate on rear of tool box. Heater bolts to plate inside above gearbox forward of the dip s/w.



Rod Jones

Inside view.


Rod Jones

Great ideas for mounting the heater. Thanks.

Declan, I'm a bit confused about your plumbing. The picture with your control valve includes what appears to be the plate at the rear of the head tapped for an outlet but you say you taped the water outlet below the thermostat housing. Did you try the rear plate first and then switch to the water outlet? Am I completely confused? Where does the water from the heater return to?

I love your beautiful metal work and I'm sure I can't come close to duplicating it.

Jud
J. K. Chapin

Jud,
I did not want to drill and tap my water jacket to fitted one of the two hose take offs as used with Arnaut heater. Used Stainless Steel tube and a ball value for water cutoff if necessary. Small inline SS ball valve works well. The old method was from the back of the head and had worked fine for 45 years but the small hose was in bad shape So went to this solution.


Rod Jones

Jud,
I wanted to test both hot coolant tapping points. The rear plate and the thermostat elbow. I never got around to testing the rear plate due to illness so it is still connected to the thermostat elbow which works just fine.
Regards
Declan
Declan Burns

Well, I really should learn to search the archives first. I've rarely had luck at that but this time I got a good hit - this thread from 2014:
https://mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&mode=archiveth&archiveyear=8_2014.dat&access=&subject=8&subjectar=8&source=T&thread=201410230130571625

I'll be contacting Ben Corsden, the Arnolt Heater expert, to order the Arnolt bypass fitting with the correct size restrictor hole.

Jud
J. K. Chapin

Mine is fitted with a DIY bracket to the upper wood bow of the scuttle; The bottom part of the heater is fixed to the hoop with 2 hose clips. One around the motor and the other one around the scuttle hoop. Both clips are interlaced.

But I can see that your heater is quite different form mine regarding the motor.

Top fitting


LC Laurent31

Bottom fiting


LC Laurent31

The factory knew how to pipe a heater, from the front of the head to the radiator return "Y" piece The XPEG had a different thermostat housing to do this. The only effective pumped flow is along the head, the cylinder walls are convection cooled with a bit of induced flow from the head flow. Google XPAG Cooling System for a pictorial of the passages.
I have a KL heater fitted and it can get uncomfortably hot, mind you I live in the UK and we do not really do cold.
Ray TF 2884
Ray Lee

OK, I think I've got this although I'm probably still confused. I like the idea of tapping into the 45 degree elbow between the head and the thermostat housing and then into the hose between the branch pipe and bypass hose which I think is the same as tapping into the bottom of the radiator. I've attached a picture showing the direction that I think water flows and where I would make these taps. Notwithstanding what follows, please let me know if this would work and if I have the water flow correctly indicated.

While annotating the picture, Ben Corsden returned my call and is shipping me the one of his Arnolt bypass fittings. It's my understanding that the fitting goes into the hose from the branch pipe to the elbow on the thermostat housing. Is this correct?

I'm supposed to be a chemical engineer with an understanding of how fluids flow but this has me bamboozled. Thanks for your help and your patience.

Jud



J. K. Chapin

Sorry (1) is the suction of the water pump it then flows internally through the block and then to the rad top. The water goes in the top of the rad and cools on the way down. The smaller pipe to the stat housing lets the pump shunt itself when the stat shuts.
Ray
Ray Lee

Jud
Does this make it any clearer?


Rod Jones

Yes Rod, that makes it much clearer. I was afraid I had it backwards. So the water pump sucks in from the side and spits out of its back into the block. Then round it goes and comes out the front of the head and goes up through the thermos housing and into the radiator.

Next question: How does the feed from the upper arm of the Arnolt type fitting, the part above the restrictor plate, get pressurized water to feed into the heater? The side outlet in my Thermo housing is a very small hole, on the order of 1/8" to 3/16" in diameter. Is this a big enough hole to feed the heater?

Thanks.

Jud
J. K. Chapin

i Am away from my car for the moment, so the only pics are in the archives here from an earlier thread. I mounted mine to a piece of black painted plywood and used a pair of Adell clamps to hang it from the big scuttle pipe. My tap is from the rear plate on the head and the other is a pickup from the “Y” tube. It is hot enough you cannot put your hand on it. I used a TR3 firewall heater fitting. I used a “push for on-push for off” button switch mounted under the dash that cannot be seen . From any viewing point on the cab side all you can see is the smith’s heater..no hoses, wires, or switches.

Regards, Tom
tm peterson

Jud,
Here's the bypass connection I used. It is a copper t-piece with a 90° bend and an orifice soldered in.
Regards
Declan


Declan Burns

Painted black


Declan Burns

Installation in bypass


Declan Burns

I've never seen so many different takes on plumbing a heater---
Basically what happens is, once the engine is started the coolant is circulated through the engine itself by the water pump, round and round it goes---As it gets up to temp. the thermostat opens and allows some hot water to pass off into the radiator and in turn some fresh cool coolant is sucked in by the pump to replace it-this flow, temp and amount is controlled solely by the opening amount of the thermostat
Now; for a heater to work properly then it needs a takeoff point, either from the thermostat housing 'below/before' the thermostat or basically anywhere along the cylinder head--there will be hot water everywhere there, possibly the hottest at the t/stat housing by one or two degrees but from that rear plate will be plenty hot enough--
Then if there is going to be a heater tap it needs to be in this 'hot' line
Now the return-this has to go in the suction side of the pump so anywhere in that black pipe in you pic posted on
--- 13 February 2020 at 01:29:40 UK time--- ,-but the closer to the pump the better--if you are going weld another dick on the pipe I'd get it close to where no.2 joins in your pic
------------------------------
For me , Best / simplest method would be to go into the back plate---complete with tap as per the pic-----

Posted 13 February 2020 at 11:28:45 UK time

and weld a fitting in as described for the return---There's a post on this forum showing where the return goes on a TF-it's where the brass bung is
Post heading----
Remove brass plug from TF branch pipe?

Keep it simple
willy
William Revit

So many ways, so few cats ...
J. K. Chapin

Jud
The Arnaut fitting has the restrictor plate between the two outlets. You do not need the restrictor plate at the take off point at the top of the this return pipe. The pump pressure side - forcing water up to the rad is what moved the water through the heater - like a bypass to the Rad. Having both restrictor plates in place wont hurt but may mean the heater will take longer to get hot.


Rod Jones

OK, that makes sense. My thermos housing is the good one from Tom L so I hesitate enlarging the bypass hole. I'll install the Arnolt bypass with the thermos housing as is and see how it works. If it makes little or no heat I can install my old thermos housing with its hole enlarged.

Thanks.

Jud
J. K. Chapin

Jud
I too have a Tom L housing and it works just fine. Heater gets warm very quickly and has no issues.
I did not change anything just installed the Arnaut fitting from Ben Corsden.

My old setup did have a restrictor plate at the take off elbow at the original header pipe - which I removed - However I fitted Toms SS Header with Thermostat and that has it built in.

On my old set up the feed to the heater came from the back of the head via an On / Off valve and needed attention. The return hose went back to the Y branch pipe into the bypass hose. Just looked a little messy but worked OK for 45 years.

The new set up looks so much tidier.
Rod



Rod Jones

Thanks Rod. That's the way I'm going to do it. I'll fabricate a pair pf stainless steel tubes to carry the water along parallel to the valve cover and use rubber hoses between them and the Arnolt fitting and between them and the TR-4 firewall brooch. I can't make it as pretty as Declan's but I can get close to how my MGB looks.

Jud
J. K. Chapin

Well, shucks. While at our club garage yesterday I stepped into a hole, fell down the sloped asphalt driveway and broke my knee cap. All projects are now on a temporary hold. Alcohol was not involved until I got home from the ER.
Jud
J. K. Chapin

Jud Hope you'll soon be able to return back to the workshop and test your heater before springs come.

Reacall of the link for water flow :
http://www.ttalk.info/XPAG_Cooling_System.htm

For sure, back plate is not hottest point. Actually, it just comes out of the pump from the bottom rad hose and through the external gallery. It is upstream the head. However, my heater hot point is connected to the back plate. It works but not very hot.
I tried to connect it at the output of the head, at the elbow pipe before the top hose. Yes it is hotter but there was no flow probably due to the bigger size of the rad pipe compared to the heater pipe.

Laurent.


LC Laurent31

This thread was discussed between 12/02/2020 and 16/02/2020

MG TD TF 1500 index

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