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I'm still debating on if I want to try it. might just place an order and see how she does. you could tie a string to the counter weight and give it a few good tugs every now and then to keep it clean.
 
I just don't know if there would be enough stack pressure to open it. Guess it depends on how heavy and well balanced it is....may just have to get one and toy with it myself too.
 
We have a couple of smaller caps like that on our irrigation pump motors which have vertical mufflers. I can tell you there is a hell of a lot more pressure coming out of an exhaust at idle, and even then the caps kind of bounce and shut. I would think when the owb is a idle it would not even crack it open which would be a smokey situation when you open the door to load the stove. I question if it would even open when the blower kicks on, a 6" exhaust cap is HEAVY!

If you are interested I have a odd cap on my boiler, I guess its a cloverleaf design? I bought it from my dealer, and hawken recommends using it. It is stainless, the top is sheilded to keep water out and heat in, yet the metal is bent to allow smoke to go up. When my owb is at idle it will make ice sikkels on the edge of the cap, so I think thats a sign it is not losing to much heat, if it refreezes the water vapor coming out of the stove. I can try to post a pic if anyone is interested, or I am sure you could see it on hawken's web site.
 
We have a couple of smaller caps like that on our irrigation pump motors which have vertical mufflers. I can tell you there is a hell of a lot more pressure coming out of an exhaust at idle, and even then the caps kind of bounce and shut. I would think when the owb is a idle it would not even crack it open which would be a smokey situation when you open the door to load the stove. I question if it would even open when the blower kicks on, a 6" exhaust cap is HEAVY!

If you are interested I have a odd cap on my boiler, I guess its a cloverleaf design? I bought it from my dealer, and hawken recommends using it. It is stainless, the top is sheilded to keep water out and heat in, yet the metal is bent to allow smoke to go up. When my owb is at idle it will make ice sikkels on the edge of the cap, so I think thats a sign it is not losing to much heat, if it refreezes the water vapor coming out of the stove. I can try to post a pic if anyone is interested, or I am sure you could see it on hawken's web site.

so it is pyramidal in shape to trap the exhaust gases near the top of the flapper and increase/ trap pressure to help open it up?

I couldn't find a pic on hawkens website or in google images.
 
We have used those caps for years on farm equipment and yes there is considerable more pressure coming from exhaust. I think they could be made so that only minor is flow needed to open them by adding a small amount of weight to the counterbalance. Should be pretty simple.
 
applefarmer;2622651 When my owb is at idle it will make ice sikkels on the edge of the cap said:
Exactly what I was trying to say. There is very little heat loss out of the stack. Funny how a couple pages earlier, we're saying the stack ID should be larger. More air flow would seemingly yield less smoke. Something to keep in mind, these little squirrel cage fans aren't turbochargers. They move air, they don't compress it. Choking the stack will only allow less air into the fire. Instead of restricting the exhaust, why not close off the air inlet a little. This would give the gasses more time to burn off instead of being pushed out prematurely. On a 290, the fan doesn't provide enough air to make this an issue. But on my old 165, there would be a flame out the pipe if the inlet door was more than half open. One mod I would consider is extending the pipe further into the firebox. Perhaps making a 45 degree mitre cut at the bottom of the extension and facing it towards the back wall with the tip 2 or 3" from the floor.
 
so it is pyramidal in shape to trap the exhaust gases near the top of the flapper and increase/ trap pressure to help open it up?

I couldn't find a pic on hawkens website or in google images.

It is more of a pyramidal cone shape and there is no flapper. I will try to get a pic for you tomorrow.
 
A guy down the road sells Crown Royal. They have a cap that looks similar to what is being described. The dealer who I have gotten to know a bit confided that a lot of guys end up taking them off because they creosote up and make a mess of the boiler. They can also block the exhaust gasses coming out according to him. No idea how true this is but if anyone knows of Crown Royals and this cap I'd sure like to know what the deal is...

The flapper design, assuming it wouldn't change weight by the amount of creosote that is deposited on it and thereby screw up the counterbalence, seems to be a better idea.

Gotta love these building blocks of ideas. While its beyond the scope of most of us, I'd really like to know the efficiency of the unit while the draft blower is on and at least as important the heat loss going out the chimney while the draft motor is on. Heat retention in the boiler is what we are all after. Less heat out the stack. Better combustion. Using less wood in a season sounds good to me.

:D
 
Caps.

I have tried these caps and 3 others. All were $70 - $95.00, They worked ok I guess in the coldest of the season when there is a lot of cycling going on in the stove. I had terrible troubles with caps in the " smolder season " when the fan is not running as often and the house is calling for less heat. They do eventually plug up with creosote. The biggest problem with them is that you can not hardly get them off when you want to snake out the flue. Something I do bi-monthly. At least with the rain cap idea you can hit it with a wire brush once in a while if it creosotes up and you can flip it back to snake the flue.
 
Hot Tip

Hot Tip of the day. Do not open fill valve, Get side tracked and return an hour later to see why you have no heat. The ice rink will be nice though.:angry2:
 
LOL!.....Now that was funny! :laugh::laugh::laugh:



Sorry to here you had some problems, but I did get a good laugh out of your post.

We all learn by mistakes!
 
Man I cant tell you how many times I've done that. Turn on the valve and grab some wood and forget all about it. Wife calls me on the phone wanting to know why there"s no hot water. Each time I say I wont ever do that again . Yea right !
 
Yeah, It pumped so much water out that the water softener regenerated 2 days early.. Wonder how much anti corrosion I lost.
 
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