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Proper installation of mod con

3zht Member Posts: 18
It seems as though every time there is a problem with a mod/con boiler it seems to be blamed on improper installation. I'm having a Lochinvar Knight 085 installed along side a new indirect water heater shortly and I'm wondering if there is anything I should make sure is present. After spending all this money I'd hate to have someone else come inspect the installation only to tell me it was done wrong.

I have seen people comment on the necessity of a LLH, magnetic filter, acid reducer, etc... what else should I be on the look out for?


  • Ironman
    Ironman Member Posts: 7,119
    You should have looked out for a competent installer first. And they're not always easy find or to know how to determine if one is competent.

    It's no so much a matter of what components should be installed as that can vary from the design of one job to the next. And installing good components doesn't prove the contractor's competency.

    If the boiler's been installed, some good pics would be helpful.

    Did the contractor do a scientific heat loss calculation like a Manual J? If not, you probably don't have a competent one.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Jean-David Beyer
  • Wellness
    Wellness Member Posts: 132
    A good place to begin is to download the manual of the boiler you are having installed and study the piping diagrams and perform your own heat loss calculation. Although having a competent installer is very important, an informed consumer also helps insure that the job is done competently.
    Jean-David BeyerBoon
    EBEBRATT-Ed Member Posts: 13,435
    I would download the manual and read it before they start. A good installer is key.

    The advise from @Ironman & @Wellness above is good advise
  • Tim McElwain
    Tim McElwain Member Posts: 4,588
    An interesting way to make sure it gets done right is attend my four day class on Mod/Cons. I just had a homeowner do just that before making the jump to a Mod/Con boiler. He said after the class it made it very easy for him to make the choice. He is in a trade so it was not a big jump for him. He is an electrician by profession.
    IronmanJean-David Beyer
  • Henry
    Henry Member Posts: 996
    If the install is not piped according to the manual nor has the recommended pumps, don't pay
  • Le John
    Le John Member Posts: 211
    @Tim McElwain what state do you teach classes in?
  • Tim McElwain
    Tim McElwain Member Posts: 4,588
    edited April 2019
    @Le john My classes are held at the Gas Training Institute in Warren Rhode Island. If you are looking for information e-mail me at [email protected]
  • lchmb
    lchmb Member Posts: 2,997
    edited April 2019
    ask your installer for pictures of previous work.. I have hundreds
    to show what I do..
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    It may be helpful, if you can find it out, if the installer has read the installation manual for the boiler he is installing. Because sometime they have not.
  • Ironman
    Ironman Member Posts: 7,119
    edited April 2019

    It may be helpful, if you can find it out, if the installer has read the installation manual for the boiler he is installing. Because sometime they have not.

    You are too kind, sir: MOST of the time they have not. It's usually used for setting their coffee cup upon it.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • We just finished installing a Lochinvar KHB 085N and really like the Grundfos 0-10 VDC circulator they supply. Installed it as the boiler pump on a LLH. I also like the 110 volt outlet they supply on the boiler; very handy for the condensate pump.

    We DID NOT do heatloss calc's. on the house. I added up the existing radiation and came to a number comfortably in the middle of the boiler's modulation range.

    I also multiplied the square feet of the house by a heatloss number which varies from 17 to 50 BTU's/square foot which I pick based on my experience over the years. I'm not perfect, but I get it pretty close and I use this figure to confirm the size of the boiler.

    We installed a LLH because there were 5 zones (zone valves), 1/2" piping to each zone. Yes, a bit strange, but only one zone exceeded 15,000 BTU's.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hourTwo btu/ per sq ft for degree difference for a slab
  • 3zht
    3zht Member Posts: 18
    @Alan(CaliforniaRadiant)Forbes what part of cali are you in? I'm in New England. I'm happy with my install and I'm just playing around with the desired set point temperature for now. I am told I can go as low as 120F with old baseboard style heaters.
  • Leon82
    Leon82 Member Posts: 684
    If you mean the fin tube base board yes you can. On mine below 115 the heat was not consistent or stable. Cast iron you can probably use lower. But don't go too low so the boiler begins to cycle a lot
  • PerryHolzman
    PerryHolzman Member Posts: 234
    The biggest reason electronics and circuit cards fail is due to voltage surges. Also, many manufactures do not build in adequate surge protection circuits (which require a sizable transformer). You need to stop those cold if you want a long life on your electronics for your mod-con.

    Also, I have read on the internet many claims about boiler manufacturers denying warranty coverage of circuit boards due to inadequate surge protection.

    Those small light weight and relatively cheap surge protectors sold in stores have a finite life as they are based on electronic components (MOV's) that degrade with every voltage surge. Some of them are actually dead by about 5 years or sooner - not that they tell you that. You have no clue. Their claim of paying you up to $50,000 for failure damage tends to be hard to collect based on a number of internet postings I've seen on that (original warranty paperwork, invoice, etc - you pay shipping back; and then they still claim it has not failed even after you have fried computers and other things after a thunderstorm with lightning); and in this case you still have to struggle with a boiler failure likely at the worst time of year.

    Old fashion transformers naturally inhibit and don't pass most minor surges; and greatly reduce the large ones.

    1:1 Transformers can be combined with some electronics (using components that don't age with every surge) to produce very good protection. These are being manufactured by:


    To the best of my knowledge these units have never failed to stop a surge.

    The same essential units are also sold by another company who sells enough to contract for their specific companies label (I'm not sure that all Brickwall products are from ZeroSurge; compare the pictures to find out).


    Of course this kind of protection, and the fact that its modest production does not come cheep. But, its cheaper than dealing with surge failures.

    It can be worth price checking between the two.

    Enjoy reading the technical literature at both ZeroSurge and Brickwall on surge protection. Its and eye opening experience for many people.

    I myself installed a commercial permanently mounted power supply for 20 Amp service NEMA 1 Enclosure as part of my mod-con 12.5 years ago (see Zero Surge Commercial FF1 product line).

    I have an assortment of plug in models in my house for critical equipment.

    Also, this does not prevent all future electronic failures. Circuit boards that use capacitors tend to die between 10 and 15 years unless the Mfr used expensive long life capacitors. Most large industrial plants with a lot of controls - and even some of the companies that sold control systems have a standing repair program where they just replace capacitors on circuit boards every decade - before failure. There are 40 year old circuit cards out there running strong - that have had a few capacitors changed 3 or 4 times before.

    I wish you the best with this,

  • NY_Rob
    NY_Rob Member Posts: 1,370
    3zht said:

    I'm in New England. I'm happy with my install and I'm just playing around with the desired set point temperature for now. I am told I can go as low as 120F with old baseboard style heaters.

    This is not a good time of year to be experimenting with circulating water setpoint curves. Wait till late late Nov or Dec to do it when the weather turns cold and stays cold even during the daytime hours. Pretty much any curve will work in May but might be absolutely inadequate in Jan.
    Keep in mind your present radiators (total overall length for the home) were designed to put out XX BTU's with 180F supply water temperature. Ideally those XX BTU's were adequate to overcome your home's heatloss resulting in a warm home. You have to design your ODR curve around your home's heatloss characteristics vs. a desire to use the lowest supply temps you can get away with without short-cycling the boiler.

    To find a working/efficient ODR curve, a good place to start would be to measure the total length of all your radiation (if fin-tube radiators- just measure the actual finned element length not the wall-to-wall enclosure) and calculate your home's heatloss at design day temperature for your zipcode. With those two figures you will be able to calculate your (theoretical) supply water temperature needed for the coldest day of the year and make an ODR curve that will keep your house warm, not short-cycle your boiler on warmer days and also keep the boiler in condensing range as much as possible giving you top efficiency.

  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    I'm happy with my install and I'm just playing around with the desired set point temperature for now. I am told I can go as low as 120F with old baseboard style heaters.

    In principle, you can go down to just a degree or so above the temperature you want the room to achieve. But it that case, the room better have no air leaks, and R-100 insulation everywhere. ;-)

    I put oversize baseboard units in my two baseboard rooms. 14 feet in each of the rooms. The original was three feet in each of the two rooms, though they were too small.

    I keep those rooms at 68F and design temperature around here is 14F. I have outdoor reset and I run the supply temperature up to 150F when it is 0F outside, and down to 120F when it is 50F or higher outside. I originally had it go down to about 100F and that supplied enough heat on warmer days, but the boiler is over-sized (even though it was the smallest the manufacturer made) and would not modulate down far enough, so it rapid cycled on warmer days. Raising the minimum supply temperature to 120F and cutting the maximum firing rate to 55% cured the rapid cycling.