Converting existing fireplaces to ventless gas
Randy2
| Posted in Energy, Heating & Insulation on
I have an classic home with massive fireplaces with massive heat loss characteristics. I would like to convert them to ventless gas. Any ideas on how to do that and what manufacturers to look at?
Replies
Talk to
Simpson Duravent and ask them about the parameters for running their venting systems thru existing masonry.
Why would you want to breath exhaust gas?
No such thing ... as ventless gas. At least I don't think there is. Closest is a kitchen range/oven, but not a heating device. Always should and MUST (by codes) vent to the exterior in some fashion. Some direct vent through e.g. the back wall/through the wall of the house, but it is vented. Good ones also provide a ducted combustion air intake ... sometimes in a double wall vent that acts as a exhaust vent, too.
You may be mistaken about what you are thinking about.
Well, there used to be ventless. They were generally limited in output (more for show than heat), and they required oxygen sensors that would shut them off if the oxygen levels in the area dropped.
Key words being "used to"
Key words being "used to"
'Bout when were the outlawed? I'm thinking they were still around five years ago.
Curious
You say massive heat loss? Do you burn in them often, and if and when you do is the furnace runing to keep up. Or do you just have the damper open and the heat runs up the chimney?
I am thinking about having one traditional fireplace in my new home and would to open to have someone talk me out of it. I am thinking that a fire twice a week in the evening would not cost me too much in energy as the furnace runs to keep up? Do you think it is worse than that?
A masonry fireplace and chimney
amount to a huge thermal wick, moving heat from the interior out into space.
An improvement over a masonry chimney would be a stainless steel flue with a damper, installed on a masonry firebox.
A further improvement would be an airtight woodstove with an outside air intake.
You need thermal mass
On a wood burning fireplace you need enough thermal mass to keep the chimney drafting after the fire starts to burn down to the nice glowing ember state, to keep the draft going in the flue. Otherwise, the combustion gasses don't get evacuated and the CO builds up in the house.
Been there, done that, got the headache from the CO poisoning.
And the down side to the ventless gas units the OP asked about is that even though the CO won't get to "poisonous" levels, it does build up in your blood stream over time, and you start to feel like you have a mild case of the flu. Even though the oxygen depletion sensor doesn't shut off the flame, and the CO detector never reaches the alarm triggering level, daily use will elevate the CO in your blood stream. You don’t get high enough levels to get sick, but you do feel like you been drug backwards through a knot hole, and beat with a big stick though.
A vented unit, that is installed with a properly sized stainless steel liner up the existing flue, and if possible and exterior source for combustion air is a lot better solution.