Outside Air Kits for Ashford 30.1's

[Ashful]

I've been battling the need for OAK's on my pair of Ashford 30.1's for nearly 10 years, and this year with opening up another floor of the house we had previously kept closed, I'm really noticing how under-powered our setup has become. A big factor in that is, as we push these stoves harder and basically run them wide-open all day everyday, we're just sucking so much fresh cold air into the house to keep them running. I notice this most in the fact that even multiple 2 gallon per day humidifiers are unable to keep our humidity much over 30%, we usually aim for 50%.

It's time to look at installing OAK's, but it does mean core-drilling some big holes thru 22 inches of rubble-stacked stone walls with only mud (not cement... literally mud) as the bedding mortar. No small task.

I successfully bored a 2-1/2" core thru a wall of similar thickness in one of our newer (1890's) additions this summer, and that went well enough, that I'm thinking I may finally try coring for OAK's on these two stoves. But the walls I'll be drilling this time are thicker and older, 24" mixed granite and red shale from 1734 and 20" all granite 1775. Whereas the one I drilled this summer might have actually had cement bedding (did not investigate), these older walls certainly do not. It makes for a much higher probability of things shifting, or the hole re-filling itself either as I work (beyond body of coring bit) or when I withdraw the coring bit. It will be an interesting "no hammer" operation, just spinning and water.

A few questions for this crowd:

1. What's the recommended kit for the Ashford 30.1? Does it connect directly to the stove, with no leakage into the room?

2. What's the smallest recommended drill diameter? The backs of the stoves are basically right up against these walls, one at 4" and the other at maybe 12", so total OAK run is maybe only 3 feet.

 

[Dieselhead]

I can’t help with 1 or 2 but have you given consideration to drilling a larger hole than needed and sleeving it with something like 3/16 so in the future if something were to shift it won’t crush your more fragile oak pipe?

 

[Ashful]

I can’t help with 1 or 2 but have you given consideration to drilling a larger hole than needed and sleeving it with something like 3/16 so in the future if something were to shift it won’t crush your more fragile oak pipe?

Yes. In fact, I will almost definitely do this, if OAK requires such a fragile pipe. But while danger of loose material collapsing into the hole may be high, I suspect the forces involved would be very low, so a simple sheetmetal duct pipe is probably sufficient, as long as it's stainless steel or something else that won't corrode under the constant dampness that is a mud-stacked stone wall.

 

[stoveliker]

Given that your home is large, air pressure differences at the OAK inlet may be significant.
This was an interesting read. I'm not necessarily agreeing with everything written (and that's not a debate for this thread), but the wind may end up being more of a nuisance with a flue top far removed from the OAK inlet, especially for your tall flue of the two.

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BK does sell a fresh air kit (for mobile home) - and I remember they have a connector piece for the stove. Beyond that I don't think it matters. I'd go rigid metal and spraypaint it with stove paint. Or insulate it if you end up with condensation.

 

[stovexxx]

my 2 cents,
the result with oak
may not be exactly what you hope for,
a lot of humidity could simply die condensed in the stone walls, or maybe not,
also evaluate the effect of the cold air directed, inside the stove,
and finally, the constant exchange of air could be not negative, without oak therefore,
these are the reasonings that I have done for myself also

 

[Ashful]

Interesting perspective, stovexxx. There's a few dozen years worth of collective experience on this forum that suggests an OAK is the solution to the shortcomings I'm experiencing, but I guess there's no guarantee.

 

[Dieselhead]

Combustion air has to come from somewhere. Either it’s coming in controlled from an oak, or it’s infiltrating from cracks and crevices. No free lunch here.
That being said I have a tight house and an oak and I still need to run a humidifier.

 

[Ashful]

Combustion air has to come from somewhere. Either it’s coming in controlled from an oak, or it’s infiltrating from cracks and crevices. No free lunch here.
That being said I have a tight house and an oak and I still need to run a humidifier.

Oh, for sure! I have a music studio above our garage, absolutely tight with spray foam insulation and a separate heating system totally independent from the rest of the house, and I still have to run a humidifier out there!

But I've experienced a remarkable increase in the demand on the humidifiers in the rest of the house, as I've started pushing the stoves harder, to keep up with the added demand of having the door to our third floor open. I've never had so much trouble keeping indoor humidity in a reasonable range with a pair of reasonably-sized humidifiers filled each day, as I've had this year.

 

[30WCF]

Oh, for sure! I have a music studio above our garage, absolutely tight with spray foam insulation and a separate heating system totally independent from the rest of the house, and I still have to run a humidifier out there!

But I've experienced a remarkable increase in the demand on the humidifiers in the rest of the house, as I've started pushing the stoves harder, to keep up with the added demand of having the door to our third floor open. I've never had so much trouble keeping indoor humidity in a reasonable range with a pair of reasonably-sized humidifiers filled each day, as I've had this year.

I don’t know what’s up there, but can you afford to close off that door again for a week and see if the trend reverses or if it’s time for some stove maintenance?

 

[30WCF]

It might take a hot minute, but you could “wash it in” if you had a hammer drill bit and enough extension rod to be outside with a water hose going, start the hammer drill on “drill only” to get the bit buried. Once it’s time for the extension, put on 3’ of extension, running through the pipe, and start drilling. Feed the pipe as you drill but have a hose shoved in the pipe full blast to wash out any slurry build up as the bit and the pipe are inserted together. You’ll have a mess when your done and the bit will have to be removed from the inside, but it should work.

If you could run a 1/2 or 3/4” pilot bit through first you could do some from the inside to start to make sure it lines up, then drill the rest from the outside. This should help with any blow out when the built breaks through. You’d just need to plug it from the inside so the water doesn’t run through while you drill from the outside.

 

[Ashful]

I don’t know what’s up there, but can you afford to close off that door again for a week and see if the trend reverses or if it’s time for some stove maintenance?

I certainly could close it again, to prove the point. But other than curiosity, I'm not sure it matters if that's the sole reason for low humidity. We know two dueling stoves, with at least one of them running full-bore most of the day, are sucking a good bit of air from the house. The more air you suck from the house, the more outside air you're bringing in and heating... and thus the dryer it will be.

I do know that when I ran the stoves on just 3 loads per day between the pair of them, I didn't have nearly so much trouble maintaining humidity. Now I'm doing more like 5 loads per day, and these being relatively large stoves, I'm probably pulling double or more the combustion air that most here have to deal with. It's a lot.

I could just buy more or bigger humidifiers, but I'm taking this as a sign that there's an easy efficiency gain to be had. I also don't love standing by the sink waiting for these enormous humidifier tanks to refill multiple times per day, only one is conveniently close enough to a jacuzzi tub for a quicker fill.

It might take a hot minute, but you could “wash it in” if you had a hammer drill bit and enough extension rod to be outside with a water hose going, start the hammer drill on “drill only” to get the bit buried.

This will be straight core drilling with a diamond tooth core drill, no hammer. Done it before, up to 3" to this kind of depth or 4" in shallower depths, not a huge problem. Yes, these are coaxially-fed water-cooled bits, not your usual 1/2" hammer drill stuff. Think much, much bigger hardware, with a 1-1/4" chuck. When drilling this type of wall, I reduce the water feed to a trickle, just enough to keep the bit from overheating.

I've never done core drilling with a hammer drill, but I suspect the core bits might not hold up so well to that, and it might increase the probability of knocking enough mud and rubble loose, so as to suffer a shift when the core bit itself passes an area and only the extension remains. Most of these core bits are 14" or less in length, so I run an extension behind them, which is only the standard 1-1/4" diameter of a core bit mounting thread. I suppose I could try to feed a sleeve in behind the bit as I work, but stuff like that often sounds easier than it ends up being, when you're in the middle of it.

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I do agree with you that working from outside in is the only way to go, as even at a trickle, you end up with a huge amount of stone slurry and water all over the ground. If I want the penetration to land near the fireplace floor, I do have to work out an accurate way of measuring and then drilling level, but I should be able to pull some reliable inside-to-outside measurements off nearby windowsills, etc.

 

[weee123]

Think of it this way, you may lose efficiency but you will have a constant stream of fresh air in to the home. Having a building completely sealed off from having any fresh air recirculating in to replace the stale air in the house is no good and results in a "sick" building.

I work commercial HVAC and a big thing we are doing in schools and other buildings are adding in fresh outside air supplies into the supply air on the units and exhausting some of the return out of the building. Due to new indoor air quality legislation buildings are required to have so many "air changes" per hour. As in all of the air in a room needs to be replaced with new outside air so many times per hour.

Granted, the way the commercial systems work is on a computer controlled damper to control the flow of outside air depending on temperature so the unit can temper the air properly as it enters the system. All of this just to say having some air leaks into a residential building is a good thing. You could do just the one stove that runs on high all day and leave the other one alone for now and see how that helps.

 

[bigealta]

His house is big and needs both stoves to heat it. But i agree, i prefer a leaky house that has fresh air constantly flowing in.

 

[30WCF]

Years ago I worked in a precision concrete demolition. We used core drills daily. If anything ever made me pucker up it was the hydraulic wall saws. Those were just a little unnerving. Not me, just some internet pics.

I am familiar with we use core drills at my work now regularly. I suspected you wouldn’t get the depth on one pass and need to remove the bit to snap and pull the core if it doesn’t break off in the bit, so I assumed you wouldn’t want to be pulling the bit in and out if you were afraid of a cave in. That is why I suggested the sleeve behind a standard hammer drill it with the hammer function turned off. All our big hammer drills have selectors to either hammer drill, hammer/chip only, or drill only. You can even go with the hammer drill function and reduce the intensity of the hammer incase you wanted to give it a gentle tap while you were in the center of the wall.

 

[stoveliker]

His house is by far not right. Being from the 1700s-late 1800s.
I don't think air quality that will be a problem. He's still going to need to run the humidifiers (indicative of humid air leaking out and dry air coming in) possibly more so because of the added chimney effect from having the third floor open.

But @Ashful, you need a King if you're running 5 loads a day through a 3 cu ft stove!

 

[Ashful]

Think of it this way, you may lose efficiency but you will have a constant stream of fresh air in to the home. Having a building completely sealed off from having any fresh air recirculating in to replace the stale air in the house is no good and results in a "sick" building.

Agreed. But this house is going to breath plenty well, stoves or no! It's very big, very, very old, and has way too many doors and windows.

 

[Ashful]

His house is by far not right. Being from the 1700s-late 1800s.

Phase 1: 1734
Phase 2: 1775 <-- largest part
Phase 3: 1894'ish
Phase 4: 1995

But @Ashful, you need a King if you're running 5 loads a day through a 3 cu ft stove!

They didn't make a pretty King. I have mentioned the idea of an Ashford 40 a few times, but maybe there's not enough market for such a thing, esp. if it requires an 8" pipe.

 

[Ashful]

I am familiar with we use core drills at my work now regularly. I suspected you wouldn’t get the depth on one pass and need to remove the bit to snap and pull the core if it doesn’t break off in the bit, so I assumed you wouldn’t want to be pulling the bit in and out if you were afraid of a cave in. That is why I suggested the sleeve behind a standard hammer drill it with the hammer function turned off. All our big hammer drills have selectors to either hammer drill, hammer/chip only, or drill only. You can even go with the hammer drill function and reduce the intensity of the hammer incase you wanted to give it a gentle tap while you were in the center of the wall.

Cool. Just wanted to make sure we were talking about the same thing. And yes you're right about the problem of having to withdraw and hammer out sections at a time, which could be my biggest problem. In the wall I drilled this fall (1890's addition), I was able to withdraw the bit, stick a tire iron into the bore and snap off a slug of rock every 8" or 10", no problem. But these bores may not cooperate as well.

And yeah, you caught the problem with sleeving... now to I remove the bit to remove core sections, if I've slid a sleeve in behind it. I think the sleeving will need to wait until all coring is done, or at least I'm far enough that I'm committed to withdrawing the bit from the far side of the wall.

And with regard to the added demand of the third floor being the source of all trouble, I guess I could be leaning into that a little too much. The reality is that I only ran 3 loads per day for mot of these last ten years, because I was never home. I would load one stove before and after work, and the other once before bed. It was all I could manage, on my former schedule.

Then I started working from home two years ago, but we've had two very warm winters, so of course I wasn't ripping thru a ton of wood. This is the first winter that I've been both working from home, and in which we've experienced more classic winter temperatures.

 

[30WCF]

Cool. Just wanted to make sure we were talking about the same thing. And yes you're right about the problem of having to withdraw and hammer out sections at a time, which could be my biggest problem. In the wall I drilled this fall (1890's addition), I was able to withdraw the bit, stick a tire iron into the bore and snap off a slug of rock every 8" or 10", no problem. But these bores may not cooperate as well.

Sometimes they pop out fine and sometimes they don’t. It is often related to the ratio of the depth vs diameter. Not long ago we were putting in some cans for flush mount runway lights. I think they were 8”x 6”deep. We had to chip every bit of every one out. Had they been 2”x 6”, they would have popped out clean. It needs to be deeper than it is wide to have a chance of snapping clean if we were talking about concrete, which we are not. You might get away with a bit more.

And yeah, you caught the problem with sleeving... now to I remove the bit to remove core sections, if I've slid a sleeve in behind it. I think the sleeving will need to wait until all coring is done, or at least I'm far enough that I'm committed to withdrawing the bit from the far side of the wall.

I like this idea. I haven’t seen that you are working with, so I’d have to trust your judgement, but I’m not sure I’m as worried about a collapse as you are. Maybe it started to crumble on you some last time and raised your concerns. Its case by case on the old stuff.

And with regard to the added demand of the third floor being the source of all trouble, I guess I could be leaning into that a little too much. The reality is that I only ran 3 loads per day for mot of these last ten years, because I was never home. I would load one stove before and after work, and the other once before bed. It was all I could manage, on my former schedule.

Correct. I wasn’t even considering the humidifier as much as I was the stoves needing to be ran as hard as they are. The third floor is the likely culprit, but perhaps it’s time for a cat at their age. I suspect you’re right and you have been maintaining the stove just fine, but it could be proof of concept, or just the fact that you are home.

Then I started working from home two years ago, but we've had two very warm winters, so of course I wasn't ripping thru a ton of wood. This is the first winter that I've been both working from home, and in which we've experienced more classic winter temperatures.

I also went from being a Superintendent to a Project Manager which means I sit on the couch everyday now and feed the fire while I punch keys on the laptop and talk on the phone. I’ve burned way more wood, and gotten more comfortable with running hotter than when I was only home every few weekends.

I think you’ll be fine with the core drill, but you know the material you are working with better than I. I’ll second Stoveliker with the rigid liner. There isn’t really any difference for what you need between electrical rigid and galvanized water pipe other than tapered threads. You could hit up the electrical supply houses or plumbing supply shops for 24-30”pipe with threaded ends. I’d probably seal around the pipe with hydraulic cement.

 

[Ashful]

Cool. Thanks, 30WCF! I appreciate your experience, here.

I'm on my third pair of cats in these two stoves. I think these ones went in about a year ago, I need to dig thru old email to verify that, but they're not very old. Since we're heating with these stoves, not just burning for fun, I make sure they're in good working order. No issues that would indicate they're anywhere near end of life, I usually get more like 4-5 seasons out of a cat on my all-hardwood diet.

As to liner, I was thinking more along the lines of stainless ductwork than schedule 40! The way stone naturally bridges, I really don't anticipate any appreciable force on whatever sleeve goes into that bore. When I talk about the hole "caving in", it's just because there's loose material inside the walls, I really don't think there's any force other than gravity on a few loose bits of rock immediately above the bore, acting on this liner.

Other holes I've bored thru stone walls, and even when removing window or door lintels, nothing more than the few small rocks or mortar bits immediately above ever fell out. Stone tends to form its own natural arch when the thing below is removed, and in my case, the thing below is my 4" hole, both small and already arched!

I just hunted and found an old photo, which I marked up for the OAK locations. We've expanded a bit since this was taken, but you can see the stone work here. Click thumbnails.

 

[30WCF]

Cool. Thanks, 30WCF! I appreciate your experience, here.

I'm on my third pair of cats in these two stoves. I think these ones went in about a year ago, I need to dig thru old email to verify that, but they're not very old. Since we're heating with these stoves, not just burning for fun, I make sure they're in good working order. No issues that would indicate they're anywhere near end of life, I usually get more like 4-5 seasons out of a cat on my all-hardwood diet.

As to liner, I was thinking more along the lines of stainless ductwork than schedule 40! The way stone naturally bridges, I really don't anticipate any appreciable force on whatever sleeve goes into that bore. When I talk about the hole "caving in", it's just because there's loose material inside the walls, I really don't think there's any force other than gravity on a few loose bits of rock immediately above the bore, acting on this liner.

Other holes I've bored thru stone walls, and even when removing window or door lintels, nothing more than the few small rocks or mortar bits immediately above ever fell out. Stone tends to form its own natural arch when the thing below is removed, and in my case, the thing below is my 4" hole, both small and already arched!

I just hunted and found an old photo, which I marked up for the OAK locations. We've expanded a bit since this was taken, but you can see the stone work here. Click thumbnails.

View attachment 335092 View attachment 335093

Beautiful spot you have there. I’d bet if you go slow with the core drill you’ll have no issues. SS should be fine with less potential for corrosion, fill in any gaps and there won’t be anywhere for anything to settle into.
For about $400 you can do it in one pass.

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[Ashful]

Wow, never seen one that deep!

So, I guess the big question is how small a hole I can get away with. If the total duct length between stove and outside is only 30" or 36" straight shot, do I need anywhere near as big as 4"?

What about 3"? 2-1/2"? 2"? I think I already have 2" and 2-1/2" bits long enough for this work. I probably would have to buy 3", and I'm sure I don't have 4".

More importantly than the bit cost, I would like to keep the hole thru this ancient stonework as small as possible. Someday, someone will surely be cursing me for making these holes at all, no matter how small they are or how many years that takes.

 

[all night moe]

From your other thread, cord cutting/streaming.

''Old houses, 'they don't build them like they used to.''
I was once told, before I got this place, "old houses mean old problems." I'm glad I didn't listen.
Lovely home you have there, Ashful. I'm not sharing with the GF. She'd be jealous for she adores stone homes. We only have a 1850 timber frame turned into a Vicky in 1906.

 

[all night moe]

I would like to keep the hole thru this ancient stonework as small as possible. Someday, someone will surely be cursing me for making these holes at all, no matter how small they are or how many years that takes.

To bad you couldn't grab air from somewhere else. Even if you had to convert to round after.

 

[bigealta]

Yup there is no way i'd drill thru that house to put in an OAK.