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Mod Con Wish List

I'm starting to get proposals for a new high efficiency boiler and indirect

HW and I wanted get opinions  on what I

should ask for and look for in the proposals.

I did a room by room Heat Loss Calculation with a spreadsheet and totaled 95,000

BTU/hr at 10 F ODT (Boston) and 70 F IDT. The HLC spreadsheet was <a href="">[color=#000000][/color]</a>

My 1988 home is 3500 sq ft on 2 levels, plus a partially heated basement

(included in the HLC but not the 3500 sq ft). Home has large south-facing

windows designed for passive solar warming. Two occupants. Jacuzzi not used in

the 2 months we've been here.

My natural gas system has 6 zones of forced hot water heat with about 272

ft. of base board radiator, of which 24 ft. is the 10" tall higher output


So far the proposals include Lochinvar Knight WHN110 with a 40 gal Squire,

an HTP Elite-110VNH with 65 Gal SuperStore, and possibly a Viessman.


The control user interface is nicer on the Lochinvar. Does this really make

a difference once the boiler is up and running? Does the less spiffy HTP

control do all the right stuff?

What are the tradeoffs of zone pumps vs zone valves?

Should service or extended warranty be part of the proposal?

There are only 2 occupants. Do I need more than the 40 gallon tank? I

understand these things can make hot water pretty quickly.

Will the Mod/Con pay back compared to a new conventional boiler and HW



  • CMadatMe
    CMadatMe Member Posts: 3,085

    You have enough radiation to heat a house almost twice the size. I'd say a mod/con will fit nicely. I'm bias towards the Viessmann Vitodens 200 with Lamda Pro combustion and limited lifetime hx warranty.. A WB2B35 would fit nicely with a 40 gal indirect.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Eastman
    Eastman Member Posts: 927
    What was the problem with your old boiler?

    Did you ever get someone out to look at it?
  • Jim100Flower
    Jim100Flower Member Posts: 88
    What was the problem with your old boiler?

    I'm going to live with the old boiler for the season and see how bad the gas bill gets then decide in the spring.

    The gas company came out and confirmed that the pressure is OK. Everyone else who's come out says there is really nothing can be done to correct the poor combustion.
  • Eastman
    Eastman Member Posts: 927
    Surely there is a reason though

    No one looked at the heat exchangers?  How long into the firing cycle did the tech's wait before taking measurements?  Perhaps the problem is that it simply doesn't stay on long enough to establish proper combustion.
  • Jim100Flower
    Jim100Flower Member Posts: 88
    Surely there is a reason though

    I don't have a lot of confidence in the MassSave home energy auditor who took the measurement after running the boiler for a minute or two. He gave me other bad information. How long does it usually take to get up to a proper level?

    No CO is measurable in the furnace room. So if I get the new boiler it will be because I expect to save money after I pay it all off.
  • Eastman
    Eastman Member Posts: 927
    I don't know

    I don't know, this isn't my gig.  And I would not think the typical home energy auditor is up to this kind of task either.  The thing is, if you never get someone to really look at it then we will never know.  Isn't that worth it? At least to satisfy our curiosity?
  • SWEI
    SWEI Member Posts: 7,356
    mod/con options

    The WHN is a good boiler based on the original Triangle Tube heat exchanger .  You might also look at the new Triangle Tube Prestige TriMax series.
  • CMadatMe
    CMadatMe Member Posts: 3,085
    Steady State Efficiency

    Boiler needs to run 6-9 minutes to reach steady state efficiency. But

    that is not realistic to how your system is running when operating under

    your norm conditions. Based on your other thread your zoned to death

    which is why we all recommended that to add the buffer tank and controls

    as well as repipe was a bad investment compared to the savings you

    would recoup.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • Eastman
    Eastman Member Posts: 927
    edited February 2013

    Hey Jim,

    Do you think it would be possible to take photos of the burner while it's running?  Frame the shot so you're right down at ground level, then have an assistant crank all the thermostats up.  (Let the place cool down for awhile first.)  Take a photo about every minute until the burner cycles off.  And snap a close up of one the flames while you're at it.  Don't get yourself killed with CO, though.
This discussion has been closed.