Anybody have a ModCon boiler?

[cantbreak80]

I'm preparing for the end-of-life of my 35 year old home heating boiler.

ModCon boilers seem to be the "hot ticket" these days but I'm curious about their reliability.
My understanding is the annual maintenance and service parts can really eat up the fuel cost savings.

This could be a real deal breaker for me even though I could probably perform all the required maintenance myself.

What experiences have you had with your ModCons...are they reliable and worth the 1st cost premium? How much does annual maintenance really cost? And, can you do it yourself?

 

[wash4me]

We are on the second year of a triangle tube prestige 250,000 btu at the wash. To achieve the condensing you need return water temperatures below around 120-130. If you have radiators etc properly sized for 180 degree water you won't save money with a condensing boiler. Likely though your radiators are over sized as most are and you could operate with cooler water most of the heating season. The boiler we have has an outdoor reset sensor so it senses the outdoor temperature and varies the temperature of the output water depending on the outside temperature. When sizing the boiler a couple things to consider. If your old boiler is 60-70% efficient be sure to reduce the btu's that you need for the higher efficiency. Another non technical way is if you've ever observed on the colder days of the year whether your existing boiler was running continuous or still cycling. Cycling drastically reduces efficiency. Ideally you have someone do a heat load calculation on your dwelling but I am opposed to paying for that so wag sizing I would knock the size down for efficiency and down again for if your old one cycled even on cold days. Take whatever you think and reduce it again by 20% and it's still probably to big! Also money to be saved by zoning the system and variable speed pumping if it's not already done.Heatinghelp.com is a place to learn.

 

[cantbreak80]

Thanks w4m...

I get it.

I recently “downsized” to this 1950s brick ranch with zero wall insulation and only 6” of attic insulation. The original single pane windows are fitted with reasonable storms.

I've run several heat loss calculations and came up with 60,000 Btu, maximum.

The existing system operates at 180F running through about 80 feet of copper/aluminum fin baseboard emitters. The boiler cold starts and once up to temperature cycles on/off about every 3 to 5 minutes.

I really like the comfort and quiet operation of the system. What I don’t like is the fuel consumption…maybe because the old boiler is a bit oversized...at 270,000 Btu!!!

I think I’ll forget about a modcon and just replace the old beast with a more efficient, properly sized cast iron boiler. I’ll use some of the 1st cost savings on upgrading the attic insulation and new windows. With those improvements, my heat loss calculations drop to about 45,000 Btu.

 

[wash4me]

You could even use a hot water heater. You would also get the benefit of the tank to store some heat and lengthen firing times. A common size of water heater is 75 gallon 75,000 btu.

 

[slamdvw]

What is the LOAD this boiler is heating water for? Someone already did the heat loss calculations, you're just replacing to the load that's already there ( the load in this case, is the radiators and/or baseboard heaters.)

That being said, I have a tankless water heater, that can be used with radiant heat or solar back up. Some can't handle the already hot water coming in on their cold side, some can.

Just doing some quick searching, your 80 feet of heaters, roughly 500 - 600 BTU/ft will be a total load of 40 - 48kbtu. The websites I seen were with a water temp of 180 degrees, 4 gpm.

Does your current system have a water heating tank, that uses a heat exchanger to heat it's water?

I am sure I missed something along the way... If you're currently firing a 270kbtu boiler... it's WAY oversized, in my opinion.

 

[Eric H]

ModCons are the latest version of the old Munchkin boilers that had a great reputation but they dropped the munchkin name for sone insane reason. I just installed my second HTP 399-elite (the next level up for ModCon), the first has been running for 2 years with zero problems.
Regarding increased service cost: i think that is just a left over myth from when the high efficiency units were new technology and manufactures were still trying to figure out how to build them and installers were trying to figure out how to repair them.
i wouldn't be concerned about increased service cost, but suggest you investigate using a 99,999 btu tankless water heater to meet your needs.
BTW: Get more insulation in that attic ASAP! You should also get a home energy audit, your gas supplier should have a free program that could pay for some heating and insulation improvements.

 

[2Biz]

CB80, I don't know if you followed my long winded thread a year ago. I installed a 199K BTU Takagi T-H3-DV demand Mod/Con which replaced my old wore out 350K Jarco floor heat boiler...Its an impressive little unit...It has a max temperature of 180° which I did test. But I only need 105° to keep the bays from freezing. Even down to 0°...Its only about $1300. There's lots of heating forums out there with people installing these things to heat garages and even homes. Maybe something to look into. I posted many links in the thread for reference if you want to look through it.

http://www.autocareforum.com/showth...-Water-Heater-For-Floor-Heat&highlight=heater

 

[2Biz]

Have you seen these by HTP...Phoenix:

http://htproducts.com/phoenix-compare.html