[[GQC] Tim]

I've noticed on the newer boilers off ebay that the top of the unit is completely closed except where the flue is placed.

On the fogwash the top is open with just two baffles/shields directing air into the flue. I haven't noticed it as such during the summer, but during the last two winters I've always had condensation problems.

A ton of hot air is expelled, not through the flue and mushroom vent, but through the opening at the top, basically venting into the van.

Might have to invest in a new properly sealed one as condensation is getting quite bad. Still need to install my Flettner as well in the mean time.

As you can see from the pics below, the flue goes straight up so no bends or blockages there.

http://tinyurl.com/nd69y2e
http://tinyurl.com/nhdw627


New 8 & 12L unit's top is closed off :

http://www.amonstar.com/photo//12l/d2.jpg

[Clever Forum Name]

Found it now. Just typed in 8l heater on ebay lol

[Small but perfectley formed]

Hi Tim the wires on the side of fog wash is that how you bypass safety feature

[Roy Harding]

Hi Tim the wires on the side of fog wash is that how you bypass safety feature

Yes Tim is that how you do it 

Roy

[[GQC] Tim]

Uhm......maybe. 

Anybody else have this problem?

[Spruce]

Hi Tim

I would be inclined to rig the heater up outside the van with some exhaust piping and see if you notice the same thing.

I would have thought that hot air rising would have created sufficient draw to not get any 'blow back'.

If it works fine in this experiment, then it could be the mushroom vent is restricting the exhaust gas. If everything was working well, then you shouldn't have needed to bypass the safety sensor IMHO.

I also feel that fitting a Flettner rotating air extractor needs careful consideration as the van will be more difficult to keep frost free in winter. Yes, it will keep the van dry by creating in internal airflow, but it will take any warmth in the air out as well.

[[GQC] Tim]

Good point Spruce. I'll try that. I don't see how it could possible restrict it, and at a loss what else to use as an exhaust.

Flettner should be okay I think, I've always got a heater in the van during sub zero temps and could do with a bit of ventilation, also the TCX-2 that I have has an adjustable bit on the inside, I can close it completely if need be.

[Spruce]

I see a couple have used this mushroom vent you are using.

Some others did go this route.

http://www.ebay.co.uk/itm/Broan-nautilus-Steel-Roof-Cap-with-Damper-634-/390655367445?pt=UK_Home_Garden_Other_Fireplaces&hash=item5af4dfd915#ht_1699wt_1141

There was a UK supplier but I don't recall who it is/was.

I'm sure Dave Willis has this vent on his van and also uses a Fogwash.

Added:

http://www.cleanitup.co.uk/smf/index.php?topic=143925.0

[Dave Willis]

What a memory! 

Yes, that's the one I've got. Had no problems with it at all but then I always work with the tailgate up anyway.

[[GQC] Tim]

I'll try and get a closeup on the mushroom vent, I actually increased the gap with a spacer. There just seems no way that is restricting anything. The gap is huge, plenty of heat coming from it, you can see it.

[Spruce]

My father in law was a builder and he once explained how important it was to build a chimney the draws the smoke out. Builders have to build the chimney to a certain height above the roof line and higher if they have 'obstacles' within a certain distance of the chimney.

I notice on all the pictures of the Reach2Clean website/Ebay over the years that he uses a Rinnai flue which is a bit higher at roof level than your mushroom vent is.

When you first posted I thought about the Rinnai 58e LPG Heater. It has a seperate cowl or hood that goes over the exhaust outlet at the top of the tank which the flue pipe is secured to. This cowl isn't sealed to the heater but has a gap which I imagine would work the same way as the Fogwash side vents.

Maybe it needs a longer exhaust pipe before it gets to the mushroom vent to create a draw. This is why I suggested you take it out of the van and set it up in a controlled environment and see if the same blowback exists. So lowering the position of the heater in the van may solve the problem. It maybe that your mushroom vent is fine, but the outside atmospheric pressures restrict the exhaust gases from escaping for some reason.

I think there is another windie who uses a mushroom vent in the center of his roof that sits between 2 ladders. For all I know the ladders may help his unit draw, or maybe he has the same problem but isn't aware of it.

I have noticed that the professionally fitted out burger vans and trailers have vents that also stick out of the roof a bit higher than yours.

I think Nat also used a Broan Flue with a Fogwash. It would be interesting to hear if he has a comment regarding this. Maybe you may have to post this on his forum.

[[GQC] Tim]

Some good points. Problem is, I can't fit the heater anywhere else due to the Grippamax, and vent wise anything higher then what I have now will look plain ridiculous.

I will temporarily take the top of the mushroom off and see if that improves anything.

[Elfyn]

Would fitting a couple of these help?

http://www.plylineuk.co.uk/acatalog/Rotating_Air_Vents.html

 

[robertphil]

spruce is correct about chimney height. years ago i had a woodburner and it kept smokin out the room . eventually i fitted 2 seperate chimneys side by side to get the draw right. twin exhausts!     one idea might be to fit a adjustable air flap inside the pipe ,these are used to control the draw  , also check that theres enough airflow praps crack a window open

[Spruce]

spruce i correct about chimney height. years ago i had a woodburner and it kept smokin out the room . eventually i fitted 2 seperate chimneys side by side to get the draw right. twin exhausts!

We had a Becker Anthracite heater in Johannesburg with an H cowl on the top to prevent wind currents blowing the smoke back inside. The heater worked perfectly once that was fitted. This H cowl also had to be a certain height above the roof - 1 meter I think it was. That H cowl was only needed when the heater was throttled back for overnight warming as the fumes going up the chimney weren't very warm.

We also had rotating vents that directed the outlet to point in the same direction as the wind was blowing. It was modelled on the same idea as those wind turbines using a tail rudder. I couldn't see that working on a vans roof, Steptoe and son's maybe, but not Tim's 

[Nathanael Jones]

I never had issues with my Fogwash & I had the same roof vent as Dave Willis,.. I reckon there's a good chance the mushroom vent is the issue,...

[[GQC] Tim]

I never had issues with my Fogwash & I had the same roof vent as Dave Willis,.. I reckon there's a good chance the mushroom vent is the issue,...

Could be, maybe the heater just exceeds the capacity of the mushroom. Do the Broan 634 come in any other colour then black?

Any pictures of installation would help greatly.

[Spruce]

Dave put a couple of photos of his installation on this thread.

http://www.cleanitup.co.uk/smf/index.php?topic=132874.0;all

I'm sure a tin of white heat resistant paint will solve the colour issue. 

[[GQC] Tim]

Dave put a couple of photos of his installation on this thread.

http://www.cleanitup.co.uk/smf/index.php?topic=132874.0;all

I'm sure a tin of white heat resistant paint will solve the colour issue. 

Thanks for that. Might even get it powdercoated.

[Dave Willis]

They are pretty tinny. I thought mine would rust away in five minutes but it's been fine. Pop riveted it to the roof and sealed it. Pretty drastic thing to do I suppose but I'm planning on running the van 'till it's more or less worthless anyway. Could always fit a rotating vent and fill the rivet holes if needed if I ever did sell it.



Just thought of something else - I'm guessing the condensation problems are driving you nuts because your windscreen is misting up?
Might be worthwhile covering and sealing the bulkhead from the heater?