Hearthstone Clydesdale TruHybrid (8492) Review

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Chaka

New Member
Jan 9, 2023
6
St. Louis, Missouri
Hearthstone Clydesdale II (8492) Review

Summary: Design flaws and poor quality control don't live up to the brand's reputation.

Last fall (2022) my wife and I purchased the Hearthstone Clydesdale TruHybrid (8492) insert to get a little bit of warmth out of our masonry fireplace. We went with this particular insert because it provided the largest viewing area of any EPA insert offered by our local dealer that would fit in our fireplace, we found it aesthetically pleasing, and we were assured by the dealer that Hearthstone was a good brand. After a full season of use we would rate is as an unqualified disappointment and encourage other prospective stove buyers to look elsewhere.

Issues with the stove:

1. The air wash. The draft sucks air in the the primary air intake, up through the side/front of the stove where it is warmed ever so slightly, and out over the top of the stove glass (see diagram attached). Testing with a smoke pen, realistically, the air wash only covers the left and right third of the glass. At lower draft (during the first 15 minutes of a fire) it tends to blow smoke rather than air over the glass. As a result, the left and right third of the glass quickly become opaque. The decision to use primary rather than secondary air means that when you close down the primary air intake for a long, smoldering burn, the middle of the glass will get sooty too. It also means the air never gets hot enough to burn off the soot. The sooty glass detracts from the enjoyment of the fire (see picture), and you will have to spend 15 minutes after each fire scrubbing with Rutland glass cleaner (once the glass has cooled down).

2. The secondary burn tubes. The Clydesdale 8192 hung secondary burn tubed underneath the baffle. The 8492 has a panel in the back of the stove to introduce secondary burn air. It's really only effective if you have a whole lot of wood in your stove and the primary air is open most of the way. You'll get to enjoy the rolling flames of a secondary burn some, but perhaps not as much as if you had secondary burn tubes on the baffle toward the front of the stove. In theory the catalyst will still convert the woodsmoke to heat, but it isn't as enjoyable to watch. In theory this new configuration makes it easier to change the baffles, but it also leaves the baffles more vulnerable to mechanical damages, ensuring that you *will* need to change them more often.

3. The primary air. It's kind of a laser beam in the middle bottom of the stove. It doesn't do a good job getting air to the corners of the stove on either side, which contributes to smoldering and sooty glass in the corners. If there's an East-West log near the front of the stove it blocks the air. Although you're not supposed to use a fire grate, it's easiest to get a fire going by building it on top of a couple of North-South logs so that the primary air can get up underneath the fire.

3. The draft requirement. This stove has a wide front and a narrow back. Unless you have a well-insulated, 33 foot, central chimney, you *will* get smoke in your house every time you open the door to reload.

4. Fiddley controls. Some owners have complained the catalyst temperature probe doesn't work. Mine works OK, but once you get the stove up to a consistent temperature (takes a few hours), you don't have a lot of margin for error between smoldering logs with no flame and overfiring. There isn't a lot of dynamic range in the primary air control. Be prepared to spend a lot of time fiddling with it. Part of the problem was Hearthston'e decision to line the stove with soapstone. Rarely does the stove get hot enough in enough places to burn the soot off of the soapstone, so it's not as if you'll get to see and admire it. It might have been better if they had chosen a firebrick material with a higher temperature limit.

5. Burn time. One of the theoretical advantages of a catalyst stove is the ability to damper down and generate heat overnight from a smoldering fire. In practical experience, if I fully load the stove and them damper down, I have about 6 hours in which I can add another log and get the fire to come roaring back. After than you will still get some heat, but the catalyst will cool below the active range and it will take some work to restart the fire.

6. Catalyst placement. The catalyst cannot be directly observed during stove operation. This makes it difficult to assess if the catalyst is successfully lighting off (normally you would look for the catalyst to glow). I see about the same amount of smoke coming out of my chimney with and without the catalyst. Taking the catalyst out it appears in clean, working order, but who knows if it's really doing anything?

7. No stovepipe damper. This is a problem for many EPA stoves, but it seems particularly noticeable for the Clydesdale. With the stove cool and the primary air control closed all the way I still get a cool draft down the chimney comparable to leaving a window open. If I had better draft, then I would simply be getting the same amount of cool air through some other hole in my house's thermal envelope and warm air going out up the chimney. This detracts from the energy efficiency of the stove. My solution is to remove the baffle, open the bypass door, and plug the flue with wool when not in use; this reduces the cool draft. But doing this every time I want a fire is no fun. The facade doesn't really leave clearance to install a stovepipe damper or a linkage to control it.

8. Build quality. As mentioned by other owners, when the stove is hot the catalyst bypass control lever can become stuck. This is an intermittent issue, so I haven't been able to get my dealer to do anything about it. Another quality issue I've noticed is that, after one year of use, the fiberglass gasket on the bypass door has fallen off. With some contorting I was able to get it back on with stove cement.

I've posted about some of these issues separately and gotten feedback along the lines of: your draft is no good, the stove isn't getting hot enough, your wood is too green, you don't know what you're doing, etc. After a full year with this stove, buying a moisture meter, buying a stove thermometer, buying kiln dried wood, etc, I can assure you the problem is the insert. Whether these are problems with my specific insert or the Clydesdale in general I cannot know.

air wash 1.png air wash 2.png soot.jpg
 
Thank you for the review! Some of the issues you've had sound like they could be due to wet wood. Have you checked the moisture content of your wood? If so, how are you testing the wood?
 
some questions:
  1. how tall is the chimney?
  2. do you have a liner installed?
    1. if so, what ID is the liner?
    2. is it insulated?
  3. is this installed in the basement?
  4. is the chimney external or internal?
  5. what was the outside temperature during said problems?
some advice:

leave a trough in the ashes from the front of the stove to the rear and try not to have the wood against the back wall "seal" on the wall.
 
Thank you for the review! Some of the issues you've had sound like they could be due to wet wood. Have you checked the moisture content of your wood? If so, how are you testing the wood?
Yes, I have tested my wood. Moisture content is 10-12% measured in the inner face of a split log. No difference using wood I've seasoned vs kiln-dried wood from the hardware store.
some questions:
  1. how tall is the chimney?
  2. do you have a liner installed?
    1. if so, what ID is the liner?
    2. is it insulated?
  3. is this installed in the basement?
  4. is the chimney external or internal?
  5. what was the outside temperature during said problems?
I have a first floor fireplace on an addition to a two story house. The exterior chimney is about 16 feet. I realize the situation is not ideal, as evidenced by cold air being drawn in through the insert when not in use (reverse draft). I have a 6 foot liner (not ovalized) as recommended by the manufacturer. The liner is insulated. Smoke spillage occurs at temperatures ranging from 20-40 degrees F. The other operating problems (e.g. sooty glass) seems to occur independent of temperature.
 
Yes, I have tested my wood. Moisture content is 10-12% measured in the inner face of a split log. No difference using wood I've seasoned vs kiln-dried wood from the hardware store.

I have a first floor fireplace on an addition to a two story house. The exterior chimney is about 16 feet. I realize the situation is not ideal, as evidenced by cold air being drawn in through the insert when not in use (reverse draft). I have a 6 foot liner (not ovalized) as recommended by the manufacturer. The liner is insulated. Smoke spillage occurs at temperatures ranging from 20-40 degrees F. The other operating problems (e.g. sooty glass) seems to occur independent of temperature.
is the addition 2 stories or is the addition 1 story?

are you reloading on coals or are there active flames still?

my procedure for reloading the shelburne is to:
  1. wait until it's only coals
  2. crack a nearby window ~1 inch
  3. open the bypass, open the primary 100% wait 5-10 minutes
  4. open the stove door 1 ", wait 10 seconds
  5. open the stove door another inch, wait 10 seconds
  6. slowly open the stove door entirely
I just increased my chimney height and with the above procedure I haven't had smoke spillage on reloads with temperatures below 40 F. Even when splits begin to smoke before I close the door smoke gets pulled up the flue. Sometimes pulling my hand out after putting in a split may pull some smoke out with it, but that's expected.

STT and Flue temperatures are usually ~250/200F respectively. It hasn't been very cold here so I haven't been running the stove hot or on a rigid schedule.

I haven't tested what happens if I were to try to reload with active flames vs just coals.
 
I'm sorry to hear about your issues. That's no fun considering the cost of the unit and install. Fortunately, our hybrid Clydesdale, installed Fall 2022, has given us only a few of issues that you've described.

1. With a 6" round insulated double wall liner of only 13-14ft we've never had an issue with smoke coming in when opening the door, provided I wait a few seconds after cracking it open slightly.
2. I agree the airwash could be better designed. Soot on the right and left lower corners stays until I clean it, but most from overnight burns off with a good hot burn in the morning. Most is open to display all the dancing flames.
In the morning I've learned to leave the door cracked until the fire is going hot again with thin and medium pieces (5 min or so) before closing. That keeps a side air wash going and prevents the smoke from sooting up the glass. Initially, I too was frustrated with the smoky glass until I started doing this.
3. The secondary inlet works pretty well for us with half to full loads. Very small fires not so much, but we don't usually do that.
4. We consistently get at 9-10 hours of good heat from a full load and have a nice bed of coals to light another fire quickly in the morning. I'm burning oak mostly.
5. I noticed the gasket surrounding the bypass coming loose when cleaning at the end of last year and I had to reinstall it. Not a huge deal, but it should have been done right from the factory.
6. The sheet metal air inlet housing at the very bottom front of the stove (under the blower control) vibrated and made noise with the blower on. I placed a piece of thick stove gasket rope under it and that took care of the vibration and noise.
7. Yes, the pretty soapstone is only pretty once, but I think it's main purpose is for even heat and distribution time.

The issues I've had seemed relatively minor to me and we've been very happy with the stove and it's performance overall.
 
Chaka,
Thanks for your review comments. We had our Clydesdale installed October 2022 and it has been nothing but an unmitigated disappointment for us. We have had all of the issues that you describe. We have to clean the glass before lighting every fire because of the soot. The fire is difficult to get started, even with wood at 10-12% moisture, and then unless we leave the door slightly ajar for about 30 minutes, it will immediately smoke up the glass. We live in a single story home with a relatively tall masonry chimney. It was installed by the dealer according to Hearthstone specifications but in the beginning wouldn't stay lit once we closed the door. Dealer had to come out (only after we complained to Hearthstone directly) and add 18" of chimney height. It works better now but is still too fussy to get started, doesn't put out the kind of heat that we need, and doesn't last more than a few hours into the night after we crash. We may look into raising the chimney further to see if that would help (but it is annoying to have to pay even more to get this thing to work up to its hype and reputation). We had a Heat-n-Glo cast iron insert in our previous home and it was a pure delight. My brother is looking for a wood burning insert and we will not recommend the Clydesdale to him, or to anyone else.
 
Does this stove have an unregulated primary boost air located in the front bottom of the firebox? Maybe too much air is blowtorching the middle of the load and not enough air wash over the glass. This seems to happen to some people and they find blocking that boost air helps. Could also just be weak draft.
 
To the folks that have a moisture content reading of 10-12%, how are you taking that reading? That’s nearly impossible to achieve in the Midwest if it’s exposed to relative humidity.