ModCon/Cast Iron Rad/Sizing/Crazy Quotes

FeelingColdColdCold

Replacing 20yo Burnham206NSL 164KBTU. Quotes all over the place. Most likely to go with Lochinvar KHB155N. Heat loss not done by any contractor but 100 yo house, brick, 2700sf, no insulation in walls, 100yo windows, all cast iron radiators. Heating bill uses 260-290 therms/month in winter. Insist on pipe clean b4 install? Water filter needed? TRVs needed if every room comfy now? Anything else? Lack of confidence from install professionals makes me ready to keep current system. Help if you can!

Jamie Hall

If the heat loss hasn't been done, you don't have any valid quotes. The heat loss is the first, and absolutely essential step, in sizing -- and thus replacing -- a hot water system boiler.

Now having said that, one reason for quotes being all over the place is differences in what is being quoted. Unless you have itemized quotes, you really can't compare them.

TRVs are only essential if some rooms cannot be properly balanced for comfort otherwise. They are only useful if there will be occasions when you want to reduce the temperature of a room. Otherwise, zoning is a far better approach.

Pipes should indeed be flushed, though not necessarily before the install -- but everything should be after the install, taking care not to flush crud into the nice new boiler, of course.

Unless your water has high solids (not dissolved, but honest to goodness solids) a filter is not needed on the feed. It may or may not be needed on the circulation -- in my opinion, only if you know you have a problem with rust/iron oxide, and then to protect the pump(s) if they are susceptible to magnetite.

Water treatment may be needed. Corrosion inhibitors are almost always a good idea. Unless your water quality is poor (particularly high chlorides), otherwise... probably not, other than the corrosion inhibitors.

But get a heat loss done.

ScottSecor

Without more details it's hard to say. It does sound like a good application for a mod con IF you can get away with operating in condensing mode most of the time. If so, a Caleffi hydraulic separator with dirt and magnetic removal would be very helpful.

Do you intend to improve the envelope of the house? If not, I don't think the mod con would make sense. With no insulation and lousy windows, I doubt you can run much cooler temperatures to the system. On the other hand, if you have huge cast iron radiators and reduce the heat loss substantially, a mod con make much more sense.

This will likely come off wrong, but here goes. As a contractor, we have a pretty good idea of what the heat load is when we pull up to the house. This is based on countless heat loss calculations over the last thirty years, paying attention to how heating systems operate during design days, how many boilers are over-sized, etc. That being said, we still do heat loss calculations on residential how water heating systems when we feel its warranted. Keep in mind that the majority of homes near me are retrofit, not new construction. In my case, if I feel the customer is just using me as a tool and simply looking at price (so his handyman brother in law can beat my price) I will not do a formal heat loss calculation. My time is valuable and I prefer to spend it wisely. For reference, it takes about two hours to do a formal heat loss calculation on the average home. This includes measuring, taking notes, entering the data, choosing the equipment and pricing same.

I have two questions for you as a homeowner. Would you be willing to pay for a formal heat load calculation? What is your location?

Zman

Your usage info will be a good way to double-check your heat loss. You will need your HDD (heating degree days) to do the math. What part of the country are you in?

Steamhead

@FeelingColdColdCold , as others have said, the heat-loss is absolutely the most important factor. Do not accept any proposal that was not based on a heat-loss.

With that said- your Burnham series 2 is still being made. It's a well-designed, well-built boiler that should last a lot longer than 20 years. I think if I had your boiler, I'd simply upgrade to a HydroStat or AquaSmart control to increase its efficiency. Is there a reason you're looking to replace it, other than its age?

Jamie Hall

I will happily second what @ScottSecor said above. A good contractor who knows his or her business will indeed have a pretty good idea what he or she is looking at for heat load when he drives up. But... he or she will still do a heat loss calculation, and quite properly may ask to be paid for it. That really is up to the contractor's practice. Considering that doing it could easily save ten times the cost -- or more -- it's cheap.

On storm windows and the envelope in general. Any improvements -- particularly in draughts, which may be the best you can do in a brick house except for attic insulation -- will pay off. However, before even thinking about replacing windows, even windows much older than 100 years can and should be reworked to get them back to tight (some of the windows I work on are going on for 200 years or more, and are still tight -- or, rather, tight again). They can then be fitted with either interior or exterior storm windows (there are advantages to either one) and give you a result which stays true to the building and is the equal of all but the very most costly modern window replacements -- and will last longer -- at less or no worse than equal expense. Inexpensive modern windows are no bargain, either in weathertightness or in longevity.

Paul Pollets

I always install TRV's on the radiators when doing this type of conversion. It enables lower temperature and individual control of each radiator and system performance is dramatically improved to work at lower water temps. Otherwise, you've been given good advice so far.

Ironman

As others have said: heat loss calc and radiation survey are the first step.
Unless you're in an extremely cold local, I doubt that your heat loss will be more than 100k btus.

bob eck

Even with no insulation and old windows there is most likely more radiation to heat the house when at design temp.
Have someone do a heat loss.

FeelingColdColdCold

Based on therms for past year (1657), HDD (6007-based on 69degrees), 99% design temp of 9 in Boston and 85% efficiency I arrive at 60K BTU Boiler. Not a J calc, but should be ballpark? Reco from the 3 "experts" is a unit 2x size. Just one zone heat here in MA, but the 164K current 20yo unit still going fine w/cast iron rads. Going oversized and therefore not condensing much seems to defeat the purpose. Brick house, old windows, storms, no wall insul because brick, but insulated attic floor which made a difference in comfort, saved about 5% in heat usage. Any main benefit of indirect HW with a unit versus keeping current atmospheric? Cost savings in HW will be small based on summer gas usage. Anyone know someone in MA who does it right and then is proud to socially distant themselves after install? Told that water problems in MA cause many repair problems with modcon. Everyone selling "the warranty." I just want it done right. Once.

EBEBRATT-Ed

@FeelingColdColdCold

Unless you existing boiler is leaking or unsafe put the money into tightning up the building envelope, windows, doors, weather stripping & insulation first. Then have a heat loss done then get quotes for changing the boiler

FeelingColdColdCold

Tightening all up as well, but MA offers 0% finance and $3000rebate-which we all know will end. Hence, the logic to get it done now.

GW

You mean $2750? Plus $400 if you get the indirect. If you’re on LP it’s a bit less

Which water heater- pros and cons to everything. Sometimes a liner is required if you keep the chimney vent water heater- that adds to your costs

Jamie Hall

May I -- perhaps rather cynically -- comment that everyone like a "free" rebate? Until you find it doesn't save you anything? It's really remarkably hard to save money by spending it.

Start off by improving the house draughtiness (but keep in mind my comments about windows -- the salesmen for the inexpensive modern sort are very persuasive...). Not much you can do about insulation with a brick house...

Then, when the boiler dies, get one sized properly to the job. If the rebate is still there, well and good. If not... so be it.

Another aphorism, perhaps: people who have and make money do so by spending only what they need to get quality, but only when they need it.

PerryHolzman

@FeelingColdColdCold

I'm a homeowner who has gone through several steps to improve my home heating. Yes I have a mod/con boiler (13+ years now); but, a reality is that it is unlikely to have paid off the cost of the install for it vs the energy savings.

Let me describe what I did and where I found the most cost effective and energy reduction upgrades.

When I purchased the house I hired a full energy audit of the house including a before and after blower door test.

The single most effective thing I did was to seal the house up once I knew where the excessive leaks were. Cost me a case of calk, several cans of expanding foam, and several days work.

The energy savings from that alone likely equaled the energy savings from replacing the boiler 6 years later when the old one started to produce and leak CO into the basement.

I also installed very energy efficient windows on 2 sides of the house. Now those are not cheap, but do make a difference. I did not have the money at the time to do all 4 sides of the house. Be careful here. In many cases modern energy efficient window replacement will not have a reasonable payback time-frame. Mind didn't, and I'm not planning on the other 2 sides of the house because of that.

Boiler replacement when the old one failed and became dangerous did produce a large energy reduction gain (I had a boiler from 1954 that was way more oversized than yours was. It was sized to heat the house with the windows open. Your 20 year old boiler is likey better sized than that.

I did make a decision to go mod/con at that time. However, the extra cost involved compared to a normal hot water boiler - and the about 5% efficiency gain likely have about a 30 year payback.

My advice to you is to hire someone to do a full energy audit on your house (with pre and post repair blower door study). Also do your best to improve insulation in the house. Windows - maybe... and perhaps you just add on an external storm window (that has to be done right to work well).

There is no reason to change your boiler until it starts to fail.

However, have your research done and know what you are going to do and how.

Go to Slantfin and download the app for your phone or pad device and do your own heatloss. Be very accurate on the data - and be very sure that you know how your walls are constructed (or be conservative).

https://www.slantfin.com/slantfin-heat-loss-calculator/

I wish you the best,

Perry

FeelingColdColdCold

Ongoing w/sealing. Wrap myself in plastic too but learned to leave small holes to breathe. Masshole save audit so I’m caulked, locked, and blown in the attic with storms added to windows. Very little left to do. Savings from all was under 10% in therms. She’s a brick house so walls cannot be insulated easily. Current boiler is 20+ and don’t enjoy the panic winter replacement and related costs. Incremental cost for upgrade to modcon negligible w/ $3000 from state.

Jamie Hall

Maintenance maintenance maintenance -- and don't think the State is going to pay you for that. But... your choice.

PerryHolzman

As you wish.

A couple things for clarification:

1) Be aware that a mod/con tends to need more maintenance and the parts are more expensive than a conventional boiler.

2) Plenty of new boilers break down unexpectedly as well.

3) The 3 heating contractors in my are would have immediately replaced my 12 year old mod/con boiler last year instead of fixing it. That's quicker for them than trying to figure out a boiler they are not familiar with where parts have to be gotten from a distance.

I wish you the best,

Perry

motoguy128

260-280 There’s there’s probably only needs 80-90k at design conditions.

To need 155, Or 140 output you’d be around 400 therms or more.

However, your have to work backwards with your current boiler efficiency and heat degree days climate data for that month.

I honestly think gas hills are more accurate than a load calculation, because it eliminate a lot of assumptions and estimating you have to use for air leakage rate caused by stack effect, wind etc.

GroundUp

Keep in mind that 60k figure is an average, not a maximum. The maximum may very well be double the average on the coldest day of the year, but the only way to know that is to do an accurate heat loss calculation. If you want to spend the time versus the money, you can do it yourself. Many enjoy the Slant/Fin heat loss calculator. Personally I hate that one and prefer the free one on builditsolar.com, it's much easier to use and much more accurate IMO. Does the Mass Saves rebate only cover condensing boilers? Figuring the lifespan and maintenance requirements of a mod/con in a high temp system compared to a regular old cast iron boiler, you're not likely to come out ahead despite the rebate.

STEVEusaPA

Based on your numbers, I come up with a rough guess of 54,980 BTU's. But if I use a Boston 'average', it puts me more at 59,500 BTU's.
That's also not taking into account if that gas was used for domestic hot water, range/stove, dryer, etc.
So without a true heatloss, still may be oversized.

GW

Steve what app is that?

GW

Perry no joke, which is why everyone is always saying hire a good contractor, one that will know what to do when it acts up (as in-the guy that installed it). It's not hard to understand- "contractor" that doesn't know the product doesn't have time to babysit a problem. We ask on every call that comes in "what kind of system" they have. 9 times out or 10 we are good to go, the other 10% need to keep calling other people.

STEVEusaPA

GW said:

Steve what app is that?

I made it myself. The concept was based on an article (and I think there was an Excel SS) by @Robert O'Brien . This one is was made with FileMaker (a database program) and is only available for IOS. You would have to download FileMaker Go from the App Store, and I can send you (or anyone) who sends me a private message a copy.
I also have a spreadsheet version for Excel if anyone wants it.
It’s just a basic guesstimate but it’s been very accurate, especially for oil.

EBEBRATT-Ed

My problem with mod cons is parts availability (have waited for parts not stocked in the middle of the winter)

And it's hard to explain to a customer that he's going to have no heat for a day or 2 while waiting for parts and the parts are big $$$$$$$$

GW

Steve is like to try and and see how it works with real world stuff. I’ll message when I have the data app

STEVEusaPA

My email is in my profile.

PerryHolzman

GW said:

Perry no joke, which is why everyone is always saying hire a good contractor, one that will know what to do when it acts up (as in-the guy that installed it). It's not hard to understand- "contractor" that doesn't know the product doesn't have time to babysit a problem. We ask on every call that comes in "what kind of system" they have. 9 times out or 10 we are good to go, the other 10% need to keep calling other people.

I understand. The local installing contractor also would replace it if they had the chance.

I'm sure you read my story; but here is a summary for the Thread Author and other new people:

In 2007 my then 53 year old hot water boiler failed and was leaking CO into my basement. I contacted local vendors for quotes. I also started internet research and found "The Wall"

I became entranced with the possibilities of mod/con boiler and specifically the design and capabilities of the Viessmann Vitodens 200.

I then asked the 2 vendors I liked best from the quote process if they were willing to start installing mod/con boilers and would install the Vitodens, with an indirect hot water heater. I was not that worried about initial price and spent additional $ to relocate the boiler to a side wall.

The installing vendor indicated that they loved the concept; but that they could not see selling more Vitodens as there were much cheaper mod/cons. They did sell a bunch of a specific mod/cons. However, later discussions indicated that every one of those mod/cons had heat exchanger failurs in the 3-4 year life range (after the mfr warranty) and they accepted huge losses and replaced them to their clients. They have sworn off ever installing another mod/con again in their life and only do cast iron boilers now.

At the same time - even though the area rep was here to teach them (and me) about how to take apart and service the Vitodens; they never paid much attention (their service man skipped 1/2 of the lessons). The result is that for annual service calls I was always the one who took the boiler apart, cleaned it, and put it back together. Their technician took a few voltage measurements (and checked the gas pressure once).

Then they showed up without any combustion analyzer for the annual service (where I did the actual boiler dissasembly, cleaning, reassembly work); with a promise to come back another day (which did not happen - even after I called and asked when they were going to do that). At that point I stopped paying them to stand around while I did the work (and I have my own voltmeter, and my own manometer to measure gas pressure and other things). I also have a multi-decade history of maintenance and instrument & control work from the US Navy, power plants, and other industrial plants; on top of my coal boiler and furnace repair days as a teenager. I'm the rare homeowner who has the right technical background. I know a retired tech who has a combustion analyzer if I have any questions on that.

Now the original installer will still help me service my boiler under the following terms. They have to supply the parts (they claim that their insurance does not allow them otherwise), and I have to pay them while I do the troubleshooting and work, as they don't know the boiler or how to do anything other than the most basic checks on it (as they have to supervise for their insurance to cover). When my boiler failed a year ago and I discussed things with them (and got a quote for the parts) - it would have cost me twice what I could do the work for myself ordering parts myself.

Of course, the original installer would have been more than happy to install a new cast iron hot water boiler if I wanted to get away from worrying about parts and service for a unique boiler in my area. They could do that the next day if I wished.

There are a bunch of my generation Vitodens installed in the Milwaukee area and I understand 2 contractors there who know how to work on them; and a supply vendor with the common parts in stock. Milwaukee is 100 miles away.

One of the vendors I got quotes on that I did not like (I thought they were rather "shady") was installing a specific mod/cons; which the internet research of the day said were not very reliable. It's been years since I've heard their name and I'm not sure they exist anymore. No idea who is servicing that brand of mod/cons in the area now. Perhaps no one.

Having a really good long term contractor install their favorite brand has real advantages. But, does not mean that there will be long term support. Parts tend to be expensive for all brands past a few year.

Perry

GW

Yes Perry 2007 was still the “early years”, we did a bunch of munchkin and then the GB142, back then. The Viessman was just beginning to get modernized with their pricing . The big issue is many heat and plumbing guys are thrilled to install a system but less eager to service it. Homeowners have no idea this is happening