What are the best applications for a Mod/Con

Steve Ebels_3

The only time I would question that a mod con would be the right choice would be a system where you have to routinely hit 180-200* in order to heat the structure. There's not a great deal of efficiency difference to be gained by a condensing boiler in that case. ROI between a M/C and a good quality CI piece is marginal when you consider the additional up front cost and the increased maintenance and service required with an M/C boiler. At least that's been my experience.

Also be aware that not all M/C boilers will even hit water temps in the 180+ range. The Viessmann Vitodens for example is limited to 170 max which may not heat a building with limited heat emmitters. To me that is the one glaring shortcoming of the Vitodens but that's a whole 'nuther topic.

Wild Rover

Mod/Con

Other than Radiant, What systems are best designed to get the most out of the Mod/Con boiler. I have a customer looking for an Oil to Gas conversion. They have a two-pipe hot water system with CI radiators. This seems to me to be a good application. Does anybody agree or disagree? Are there any other systems that could support the installation of a Mod/Con. Thanks.

[Deleted User]

perfect situation

Cast iron radiators are perfect for mod/cons. You can run reall low water temps through the rads and make the boiler condense all the time. Constant circulation with trv's is a great way to heat a house. Make sure you use a wye strainer on the return to prevent rust from damaging the heat exchanger.

Steamhead (in transit)

Make sure

you have a good location for the sidewall venting all mod-cons need. In most cases that's a foot over the highest recorded snow accumulation and 3-4 feet to the side of a window or other penetration. Most old houses we see don't have any place to vent a mod-con. In Baltimore we've had as much as three feet of snow.

Think about it. If there's enough snow to cover the inlet and outlet, and the boiler quits as a result, will they be able to get the truck to your house quickly to fix it?

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Unknown

side wall

side wall venting is just an option not a necessity with mod/cons, an existing chimney would work well as a chase for the new venting, just check that the max developed length is not exceeded.

Steamhead (in transit)

"just check that the max developed length is not exceeded"

It probably would exceed it except on some 1-story buildings.

Failure to pay attention to things like this is one factor in carbon-monoxide deaths. The lawyers are coming, the lawyers are coming.....

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Unknown

Many mod/cons allow venting length enough to pass through many stories: Triangle Tube Prestige being just one I have installed in this very application. As long as you follow the manufacturers venting practices I don't see how this would be a problem, and anyways mod/cons are sealed combustion thus making them much safer than any atmospheric appliance. I believe the lawyers would be on their way if you were negligent in installing anything.

Timco

I had a cust last week ask for a price on a particular mod con, but he explained he was using a HX between the boiler and the system. I told him that he would likely not see the low return temps needed to make the most of a mod con and could save $ and just put in a mod only type unit and get the same results...

Tim

Floyd_50

Side venting

Hey Steamy,
You can go out the side and then elbow up and out to get any clearance you need for snow. Have done this many times.
Can't really think of anything other than some really screwy installs that were really baseboard challenged that I would'nt install a M/C.

Floyd