Heater diverter valve
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Discussion

AndrewT1275

Original Poster:

911 posts

269 months

Tuesday 23rd June 2020
quotequote all
Posting in here rather than the technical section as this forum has the widest range of obscure vehicle knowledge.

I'm after a cable operated valve that will receive water from the cylinder head and in one position let it flow back to the radiator but in the other position let it flow through the heater matrix. A simple open/closed valve won't do as it needs to have a continual flow out of the cylinder head.

Something like this but it needs to be cable operated:



There are 4 way ones which I could get to work with a little bit of extra pipe work but it will make the engine bay look a mess so I'd rather avoid that if possible



My Googling skills are letting me down so can anyone think of a car that used a heater valve this as standard fitment with a cable pull? A nice metal one would be better than plastic and preferably from something mass produced and readily available such as a BL product rather than something that was only fitted to a Miura during one month of production.

Mike-tf3n0

573 posts

111 months

Tuesday 23rd June 2020
quotequote all
Have you spoken to T7Design, they make all sorts of bespoke heaters and might have something.

AndrewT1275

Original Poster:

911 posts

269 months

Tuesday 23rd June 2020
quotequote all
They only seem to have the on/off and 4 way ones.

838HNK

605 posts

248 months

Tuesday 23rd June 2020
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Sorry wrong side of the pond but this looks closer ...

https://www.ebay.co.uk/itm/CABLE-OPERATED-BYPASS-H...

|https://thumbsnap.com/eTeuihLb[/url]

AndrewT1275

Original Poster:

911 posts

269 months

Tuesday 23rd June 2020
quotequote all
Thanks but that's the same as the 4 way one I posted above.

I could use one of them but that means re-routing the existing heater return across the engine bay to the valve and then back cross again to the pump. A three way one would be a much neater solution.

9xxNick

1,159 posts

243 months

Wednesday 24th June 2020
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Do you have a diagram of the current coolant circuit that you could share?

AndrewT1275

Original Poster:

911 posts

269 months

Wednesday 24th June 2020
quotequote all
Not one that would be any use as that's what I'm looking to change. Just need a valve with one input and two outputs with a cable operated mechanism to vary the flow between the two outlets.

//j17

5,057 posts

252 months

Wednesday 24th June 2020
quotequote all
Is this something very old/odd that you're trying to replace an unobtainable valve for, because "heater OR radiator" is a very uncommon set-up, which is why you're struggling to find one. I mean do you really want to stop ALL water going through the radiator when you put the heater on?

Most cars just have a T piece in the pipe going to the radiator and the heater valve sat off of that. Open the valce and some of the hot water starts flowing through the heater matrix but the rest still flows through the radiator. If you can't find an all-of-nothing valve is modifying the set-up to work like that an option? Certainly the Triumph world could provide you a cable operated valve that worked in that set-up.

AndrewT1275

Original Poster:

911 posts

269 months

Wednesday 24th June 2020
quotequote all
hehe No it's a mini which is about as common as you can get.

The heater take-off is at the far end of the cylinder head from the pump and thermostat. With the heater open or closed the water still goes through the rad as it exits at the front. Modified engines can suffer from hotspots at the no 4 cylinder as the flow isn't so great there and a common 'fix' is to just keep the heater tap open to allow greater flow and circulation at that end of the head.

The downside of this is that the heater is always on so I thought a neat solution would be to put in an extra hose that would effectively be a heater bypass.

If the valve I'm after doesn't exist then I won't bother trying but I'm surprised that such a thing doesn't exist somewhere. More modern cars have them as per the photo above but they aren't cable operated.

AndrewT1275

Original Poster:

911 posts

269 months

Wednesday 24th June 2020
quotequote all
I'm trying to put in a heater bypass, not a stat bypass.

AndrewT1275

Original Poster:

911 posts

269 months

Wednesday 24th June 2020
quotequote all
You are misreading it. A normal open/close valve won't work.

I want the heater take-off from the cylinder head permanently open to encourage better coolant circulation.
However I don't want the heater permanently on.

An open/closed valve would mean flow on + heater on or flow off + heater off.

I need the option of flow on + heater off or flow on + heater on.

The valve I've described is the best way of doing this and I'm trying to find out if they exist in cable pull form. I thought I'd seen similar used by Fiat or Alfa in the 60's or 70's but can't find anything now.

//j17

5,057 posts

252 months

Wednesday 24th June 2020
quotequote all
So if my mental fag packet sketch is correct you can 'assist' cooling the rear of the head by turning the heater on - not so much because you have heat being removed via the heater matrix, but more because having it open means you have water actually flowing out the back of the head to the rad, it just happens to go via the heater matrix (and make you hot in the summer)?

If that's correct then you could start by running a hose from the head outlet to the heater return. That gets you your additional cooling but no cabin heater so cut that new hose near each end and plumb in a pair of T-pieces. You then just need to run a hose from the block outlet-end T-piece to the heater valve inlet, and a second one from the heater matrix outlet to the radiator-end T-piece.

I don't know mini's so that's assuming the heater valve isn't directly mounted to the head. If it is you just need to tweak things slightly. Disconnect the standard heater valve in the open/hot position, then add the first T-piece after that. Rather than running direct from the T-piece to the heater marix inlet you rather run from the T-piece to a secondary heater valve, then secondary heater valve to heater matrix inlet. Finally connect the heater control cable to the new valve and you're done.

AndrewT1275

Original Poster:

911 posts

269 months

Wednesday 24th June 2020
quotequote all
//j17 said:
So if my mental fag packet sketch is correct you can 'assist' cooling the rear of the head by turning the heater on - not so much because you have heat being removed via the heater matrix, but more because having it open means you have water actually flowing out the back of the head to the rad, it just happens to go via the heater matrix (and make you hot in the summer)?

If that's correct then you could start by running a hose from the head outlet to the heater return. That gets you your additional cooling but no cabin heater
Yes, that's exactly right.

//j17 said:
so cut that new hose near each end and plumb in a pair of T-pieces. You then just need to run a hose from the block outlet-end T-piece to the heater valve inlet, and a second one from the heater matrix outlet to the radiator-end T-piece.

I don't know mini's so that's assuming the heater valve isn't directly mounted to the head. If it is you just need to tweak things slightly. Disconnect the standard heater valve in the open/hot position, then add the first T-piece after that. Rather than running direct from the T-piece to the heater marix inlet you rather run from the T-piece to a secondary heater valve, then secondary heater valve to heater matrix inlet. Finally connect the heater control cable to the new valve and you're done.
The valve is normally attached to the head but I can put a normal elbow in its place and tee off after that as suggested. What you've described is one of my fall-back solutions if I can't find an appropriate twin output valve.

838HNK

605 posts

248 months

Wednesday 24th June 2020
quotequote all

You were lucky ... oooppsss sidetracked.

I ran my Mini (DSF 821L where are you now ...) with the heater on full tilt and the windows down.... probably so that it felt faster.

998 - single SU - 731 cam - 12G295 head - no exhaust and adjusting the drum brakes was a weekly exercise ....


mog1275

23 posts

136 months

Thursday 25th June 2020
quotequote all
AndrewT1275 said:
hehe No it's a mini which is about as common as you can get.

The heater take-off is at the far end of the cylinder head from the pump and thermostat. With the heater open or closed the water still goes through the rad as it exits at the front. Modified engines can suffer from hotspots at the no 4 cylinder as the flow isn't so great there and a common 'fix' is to just keep the heater tap open to allow greater flow and circulation at that end of the head.

The downside of this is that the heater is always on so I thought a neat solution would be to put in an extra hose that would effectively be a heater bypass.

If the valve I'm after doesn't exist then I won't bother trying but I'm surprised that such a thing doesn't exist somewhere. More modern cars have them as per the photo above but they aren't cable operated.
For an alterative solution
Same issue as my Minor but I plumbed mine in with a Mini remote heater valve & have teed a restricted bypass across it to allow flow when the heater is off (heater still works fine)
If doesn't make sense I can post a picture of the pipework if you want
I like the idea of the three way valve though I may do it myself if you find a suitable one.