Heat not that hot. Later E model.

[BloodRedSkies]

So with my 'E' I flew it in the coldest weather I have so far as it's my first winter in Minnesota with this plane. The air from the heater was not hot. I want to see what my expectations should be because I never had complaints about our 231. This is the coldest plane I've flown in MN. 

Just to rule out operator error. There are the two push pull control for 'heat ' and 'ventilated air', the lower pedestal vent control lever, and the two footwell butterfly valves. With the ventilated air closed and heat on full the air coming out the center vent was warm not hot. It was -11c out and my engine seems to run cool 24/24,  267-312 deg chts I have the power flow exhaust.

The back seat would have been unbearable. So what are the obvious things to check? Tubing? Air getting passed the ventilated air valve? Other places in the plane that leak air also (overhead vent, baggage door etc?) What is normal heat from an E or F? 

[Shadrach]

17 hours ago, BloodRedSkies said:

So with my 'E' I flew it in the coldest weather I have so far as it's my first winter in Minnesota with this plane. The air from the heater was not hot. I want to see what my expectations should be because I never had complaints about our 231. This is the coldest plane I've flown in MN. 

Just to rule out operator error. There are the two push pull control for 'heat ' and 'ventilated air', the lower pedestal vent control lever, and the two footwell butterfly valves. With the ventilated air closed and heat on full the air coming out the center vent was warm not hot. It was -11c out and my engine seems to run cool 24/24,  267-312 deg chts I have the power flow exhaust.

The back seat would have been unbearable. So what are the obvious things to check? Tubing? Air getting passed the ventilated air valve? Other places in the plane that leak air also (overhead vent, baggage door etc?) What is normal heat from an E or F? 

Something is likely in need of adjustment or there is an issue with the plumbing. Bottom line is that mixture setting and OAT affect output but it should still perform adequately under very cold conditions. I put together some heater temp output data a few years ago. Even at 7° OAT I still had a surplus of warm air.

 

 

 

[N201MKTurbo]

I would check the seals in the heater valve. My 67 M20F would cook you out on the coldest days.

[Boilermonkey]

I have chased the heat issue in our M20M to no end.  New seals seem to not really seal all the way.  The simple owner approved modification is to stuff a rag in the cabin air inlet.  Still warmish at best, but better than nothing.

[Ragsf15e]

1 hour ago, BloodRedSkies said:

So with my 'E' I flew it in the coldest weather I have so far as it's my first winter in Minnesota with this plane. The air from the heater was not hot. I want to see what my expectations should be because I never had complaints about our 231. This is the coldest plane I've flown in MN. 

Just to rule out operator error. There are the two push pull control for 'heat ' and 'ventilated air', the lower pedestal vent control lever, and the two footwell butterfly valves. With the ventilated air closed and heat on full the air coming out the center vent was warm not hot. It was -11c out and my engine seems to run cool 24/24,  267-312 deg chts I have the power flow exhaust.

The back seat would have been unbearable. So what are the obvious things to check? Tubing? Air getting passed the ventilated air valve? Other places in the plane that leak air also (overhead vent, baggage door etc?) What is normal heat from an E or F? 

I fly my f in a little colder temps and it’s better than you describe, but around-15c, I’m wearing a jacket and hat.  Id check your butterfly mixing valve first.  Sealing up leaks in the baggage area (door and far back corner to battery) help the back seat.  You can also remove the carpet and seal up leaks in the floor.

[BloodRedSkies]

3 hours ago, Shadrach said:

Something is likely in need of adjustment or there is an issue with the plumbing. Bottom wine is that mixture setting and OAT affect output but it should still perform adequately under very cold conditions. I put together some temp output data a few years ago. Even at 7° OAT I still had a surplus of warm air.

 

 

 

Exactly what I'm looking for. I'll do that tomorrow with my laser therm if I have time. 

[cbarry]

I would check the condition of the source of the heat, the muffler and the shroud/collector as possible causes for lack of heat.  Then check the condition of the inlet and exit of the muffler shroud ducts for leaks.  Also, if your cowl flaps are open or have been adjusted to be in trail when closed, you may have reduced heat in the cabin (the air flow leaving engine compartment will be greater and draw heated air away from the firewall cabin heat box/control flap the more the cowl flaps are open).  

[RLCarter]

Check all the scat/sceet hoses (ducts)mine was original and not in the best of shape , the rear seat hose runs behind the LH side panel and gets crushed shut over time. Full disclosure I never run cabin heat here in S. Texas but I did replaced all the hoses due to their condition 

[Shadrach]

3 hours ago, RLCarter said:

Check all the scat/sceet hoses (ducts)mine was original and not in the best of shape , the rear seat hose runs behind the LH side panel and gets crushed shut over time. Full disclosure I never run cabin heat here in S. Texas but I did replaced all the hoses due to their condition 

I have never seen a “rear seat hose”. My parts manual does not seem to show it. Can you elaborate on its location?

[RLCarter]

11 hours ago, Shadrach said:

I have never seen a “rear seat hose”. My parts manual does not seem to show it. Can you elaborate on its location?

This was on a 65 “E”, it was a small 1-1/2”(ish) hose that ran from under the panel on the pilot side down the left side and exited just above the floor in the rear. I’ll see if I have a picture of when I gutted the interior, I remember it was a pain snaking the new hose due to all the structural tubing 

[AndreiC]

I have a similar problem. In my 1970 E I think the three problems are

1) the cold (ventilated) air distributor (on the passenger side, inside firewall) does not seal completely -- where does one find seals for it? It is just a rectangular metal plate that slides into some guides and blocks the airflow from the intakes on the side of the airframe;

2) the hot air valve leaks some of the hot air leak back into the engine compartment in the spot where the cable controlling it goes inside it (this valve is located on the firewall right side, inside the engine compartment; the previous owner had put some caulk on the place where the cable goes into it, but I removed it as I thought it was an unsightly repair);

3) since the seals to the main cabin door have been recently replaced, the door does not close quite right and I think I have some leaks around it. 

In my case, flying with the heat full on and the ventilated air closed, it is reasonably comfortable with just a sweater in the front seats. But in the baggage compartment, small pieces of ice did not melt in a 2 hour flight, so it was cold. This was in 10 dF OAT.

[Shadrach]

9 minutes ago, Andrei Caldararu said:

I have a similar problem. In my 1970 E I think the three problems are

1) the cold (ventilated) air distributor (on the passenger side, inside firewall) does not seal completely -- where does one find seals for it? It is just a rectangular metal plate that slides into some guides and blocks the airflow from the intakes on the side of the airframe;

2) the hot air valve leaks some of the hot air leak back into the engine compartment in the spot where the cable controlling it goes inside it (this valve is located on the firewall right side, inside the engine compartment; the previous owner had put some caulk on the place where the cable goes into it, but I removed it as I thought it was an unsightly repair);

3) since the seals to the main cabin door have been recently replaced, the door does not close quite right and I think I have some leaks around it. 

In my case, flying with the heat full on and the ventilated air closed, it is reasonably comfortable with just a sweater in the front seats. But in the baggage compartment, small pieces of ice did not melt in a 2 hour flight, so it was cold. This was in 10 dF OAT.

You might also check the duct that goes from the NACA duct on the passenger side to the defuser behind the radio stack. There is a little elbow at the inlet that adjusts the valve. It need not be open in cold weather.

The caulk you cleaned off was likely a dab of RTV. Perhaps you might reapply in a more “slightly” manner.

[cliffy]

2 issues-  hot air coming in and cabin air going out

I found that the cabin on my D sucks air from the tail cone into the baggage area in great volumes (cold air wanted in the summer

but not the winter)

As a test I made a foam (3") plug that goes on the top of the rear seat and seals the headliner fully left to right

It works great in the winter and even better after I sealed all the holes in the rear baggage bulkhead from inside the tailcone.

Make sure you are not losing LOTS of air out of the main cabin door seal

Use a tissue in flight to see if it is sucked up into the door jam around the seal areas. You can lose lots of heated air here. 

I would postulate that if the door seal leaks -- that is why the air is drawn from the tailcone to the cabin

The shape of the fuselage around the windshield/door area leads me to think it is a low pressure area just ripe to suck air out of

the cabin and bring in cold air from the tailcone faster than it can be replaced by the hot air coming in. 

[Shadrach]

Cabin leaks or no leaks, if he has the same set up that I have in my 67, he should have very high temp at the vent. Depending on mixture setting, mine measured between 155° and 175° at an OAT of  7°. At merely freezing OATs it’s pushing close to 200°.  There is no ambiguity in whether or not the system is working properly…if it is, you can hard cook an egg with it.