Cover circulating louvers on a Monessen fireplace

[floatsonwater]

Long story short, I had just had three fireplace installed which were all supposed to be radiant firebox's. To my surprise, they installed one circulating model which is a Monessen SC42A. I was told it wasn't a big deal and I could take the louvers off and cover the hole with a steel plate and stone over it. Since I'm not using a circulating fan, it seems like a plausible solution. If it matters, the firebox is also using a fresh air intake from the outside for combustion.

Given the remodel timing and stone being ready to go up, using the steel plates is by far the preferred solution if its safe. My concern is if the louvers also double as a method of cooling the box. From the nifty animation below, it seems the cooling is from the outside air through through the double wall flue and the louvers just are just for heating the room. I did notice some additional intake vents at the top of the firebox opening (you can't see them unless you look up). These would not be covered/blocked.

Any thoughts from someone that know more about this than me?

 

[DAKSY]

I moved this to the Hearth Room. Your unit, according Monessen, appears to be a wood burning fireplace.
The animation you show is representative of a Direct Vent Gas Burning fireplace.
Without sounding too condescending, are you sure of what you have installed?

 

[floatsonwater]

The model number I posted is correct. The diagram I found online and as you just pointed out, apparently does not represent the model I have. That's my bad.

It is a wood burning fireplace, but is set up with a gas log set.

 

[begreen]

If this were in my home I would have the same concerns and would not block the louvers without guidance from Monessen, preferably in writing.

 

[floatsonwater]

I'm going to try an call them today, but I have a feeling they will just say use the other firebox even though it may be perfectly fine to cover the louvers.

 

[floatsonwater]

Tried calling Monessen but they just have a recording saying to contact your local dealer. My local dealer said to cover them, but I would still like some additional confirmation.

Any dealers out there that have a direct contact with Monessen they could ask?

 

[bholler]

i really don't think you should cover any vents with out being told specifically by the manufacturer and like bg said get it in writing.

 

[floatsonwater]

Since I couldn't get a clear answer I decided to run a study to obtain objective data. I strategically placed 7 thermocouples on the exterior of the firebox, as well as the inside cavity of the upper louvers and even inside the burn area just above the log set. Each thermocouple was read by lab calibrated thermometers. I ran the first test with the louvers open and the second with the louvers covered. Each test was run for two hours and temperature was measured in 30 min intervals. I ended up extending the covered test to 5 hours and that data is the 3rd attachment.

Red lines are covered temps, blue lines are open louvers. The hottest temps were all measured in the cavity of the upper louvers. The exterior of the firebox on all sides maintained very low temps in both cases.

Based on my study, I'm not to worried about covering the louvers. Thoughts?

 

[webby3650]

With a gas log there is no way you will have an issue. The issues will arise if a future home owner decides to burn wood. These units are designed and engineered to be safe if operated in the manor which the manufacturer lays out. These ZC fireplaces are complete systems, anytime you deviate from the way it was designed, you run the risk of problems. Even more, any issues that arise will all be on you, insurance coverage won't be an option.
As a rule of thumb, it's never acceptable to cover louvers on a ZC fireplace. The only exception would be if the manufacturer says its ok and they most likely won't, after all that's why they make a model with no louvers. You should have the installers Install the correct unit in my opinion.

 

[floatsonwater]

I don't disagree that burning wood would cause it to run hotter. However, it seems that based on the data I collected, the circulation model fireplace is simply for the added benefit of adding a blower and has no affect on the overall exterior operating temperature of the fireplace. I'd be willing to bet that burning wood would yield similar results. But, I'll leave that study to someone else.

 

[webby3650]

These fireplaces have to be installed as if wood is the fuel. Since they are approved for both.

 

[webby3650]

I have replaced 3 or 4 ZCs just like yours in the last few years with new high efficiency units, because the old unit burn the end of the house off. These were even installed properly, they were just over fired. These things have minimal tolerances, they really shouldn't be altered.

 

[floatsonwater]

I'm surprised the one end my house didn't burn off before. When the old fireplaces were demoed, they were literately packed tight with blown in insulation that one would normally use in an attic. It was packed tight around the firebox, around the flue, even in the holes at the base of the flue where it connects to the firebox.