Seeking your thoughts regarding a boiler/system upgrade for a small 1980s ranch.

Hugh Mason · March 1

I'm considering putting a purchase offer in on a 900sf mid-80s ranch that's heated with a boiler of similar vintage in what appears to operate a single loop with the whole house including the basement are controlled via a single thermostat in the living room . The basement is unfinished so there's excellent access to piping. The old boiler and close in piping looks pretty sketchy with one section of pipe having 3 valves in a row with two being redundant or more likely seized up. I suspect that 2 or 3 zones might add to comfort and would even consider a condensing boiler and perhaps larger/lower temp emitters if that would add to comfort.

So what do you think? Just throw in another 80% cast iron unit of appropriate output and refresh bits that need it? I'm in my early 70s so this is in all likelihood the last house I'll live in.

Thanks so much for your well earned advice.

Hugh

Jamie Hall · March 2

If it ain't broke, don't fix it.

Does the present system work? Will your building inspector for the sale test it? He or she should…

If it does need a new boiler, get it sized correctly to the load. I wouldn't spend the extra to save the 5 percent or so on what a mod/con might give you.

jesmed1 · March 2

I am not a heating pro, just a homeowner/engineer. The very knowledgeable heating pros here will give you good advice. Meanwhile, a few questions and thoughts.

One important factor is going to be your type of radiation. You say mid-80's construction, so I'm assuming baseboard radiators? How many linear feet? And where in the country are you, as your local climate will affect how much heat you need.

We have two cast iron boilers in our 100-year-old 4-unit building with cast iron radiators in the Boston area, and the cast iron boilers work well with high-water-volume, high flow rate systems with big old pipes and cast iron radiators. But they can be problematic on systems with smaller water volumes and lower flow rates through smaller diameter pipes and baseboards. Especially if you split one relatively small zone (900 sq ft) into even smaller zones. The boiler heats the relatively small volume/low flow rate of water very quickly, then short-cycles on the high limit, resulting in inefficient operation.

With 900 square feet, you're unlikely to need more than, say 30,000 BTU/hr depending on where you are and how much insulation/air sealing you have. That already puts you in the very low end of cast iron natural gas boilers. And if you are going to split zones, you may want to reduce the output even further. So I'm guessing the heating pros may recommend a modulating condensing boiler that can reduce output further for smaller zones.

But meanwhile, if you can answer the questions about your radiation type, linear footage, and your location, that will help them give you better answers.

Hugh Mason · March 2

Thanks for the detailed reply. The house is in climate zone 5A. It's a modular with 2X4 walls and decent looking insulation in the attic. It has all new windows and doors. I can measure the lineal footage of baseboard this Tuesday when a get a chance at a second inspection. The purchase offer is due on Wednesday so I'm working to line all my ducks up. The basement walls are uninsulated but I plan to rectify that if I go ahead with the purchase.

jesmed1 · March 2

I think the short answer is that the house is so small and the pipes easily accessible, so any problems with the system as is now shouldn't be hard to rectify.

Once you get in there and assess how the existing system is working, then you can make better informed decisions about where to go from here.

EBEBRATT-Ed · March 2

I had a 1000 sq ft ranch that was like a seive and 50,000 btu with 90 feet of baseboard it what it needed. Yours is certainly better insulated and better windows so 40,000 is probably a decent guess.

That being said there is no need to install a larger boiler than the radiation will need.

If it was me, I would use a standard CI boiler and either keep your water tank or install an indirect off the boiler.

If you have an outside chimney which I suspect you probably need a stainless steel liner. A good chimney sweep can do this. You might call one and get a #.

Look up the cost of a new 40,000-50,000 btu CI boiler on line and multiply the cost x4 and you will be in the ballpark.

Peerless or Weil McLain are good choices. Supply House.com has the #s

The biggest obstacle is a good contractor, unfortunately many of them suck.

When your ready post your location or check "find a contractor" on this site. We may know someone who can help.

Hugh Mason · March 2

Perhaps I'm interpreting this wrong when you mentioned "Look up the cost of a new 40,000-50,000 btu CI boiler on line and multiply the cost x4 and you will be in the ballpark." Should I take that to mean to install a new cast Iron boiler ought to cost 4 times the cost of the boiler alone? It's not quite a plug and play operation but jeepers that seems spendy. It appears that many of the better regarded CI boilers are about as expensive as a small Lockinvar mod-con that would purr through the shoulder seasons with a good deal of efficiency.

pecmsg · March 2

I wouldn’t use the home inspector for evaluating the boiler. Have your tech look at it.
yes 3 or 4 time the onLine cost for install.
Get into the trade and see what has to be done!

hot_rod · March 2

https://forum.heatinghelp.com/discussion/comment/1846180#Comment_1846180

You are wise to consider a mod con. The modulation alone is worth any small price increase. And as you noticed CI boilers are not always less $$.

The more you can condense it the better the efficiency. If you plan on zoning it makes even better sense to have a mod boiler.

In my area labor rates can run from 50- 300 bucks an hour, so that is a big part of the cost.

We did this issue to help people make decisions for low temperature operation and conversions.

https://idronics.caleffi.com/sites/default/files/magazine/file/Idronics_i35_0125-compress.pdf

Hugh Mason · March 2

Thanks for the link Bob,

Zoning the system seems like it could potentially increase the comfort of the place but then again I've not lived in it yet. With some luck I'll get to spend a bit of chilly spring in the place to get a feel for how it currently heats.

Hot_water_fan · March 2

I’d consider this the 50th highest priority thing for a new house. Get it inspected and then don’t think about it.

Hugh Mason · March 2

https://forum.heatinghelp.com/discussion/comment/1846236#Comment_1846236

Yes, but I've already looked at the 49 that rank above this;)

jesmed1 · 12:30AM

Most home buyers never make it past number 3. 😅

LRCCBJ · 12:46AM

Zoning the system seems like it could potentially increase the comfort of the place

The only way it increases the comfort is if the installed radiation is wildly in error as compared to the heatloss of the individual space. This is highly unlikely.

I'll tell you a story of one of my houses where, at a younger age, I decided to separate the single thermostat and zone on the first floor in a 100 year old Dutch Colonial (1900 square feet) into NINE Zones. It was not as difficult as it sounds as all the rooms had the 3/4" piping extend directly to the basement so putting nine zone valves down there together with 1" copper for the mains was not a massive effort. All the asbestos clad 2" iron came out and the 1" copper was installed over the course of about two years when I had the time. Did one half the building at a time.

The interesting thing about this story is that NONE of the zones on a given floor could be controlled greater than about 6°F. The energy from the highest zone would migrate over to the lower zones to the point where the lower zones would never call. The only way to increase the 6°F was to keep all the doors closed at all times………..which is possible in a 100 year old Dutch Colonial (because they all had doors)……………likely impossible in newer more open buildings.

I will say that the project eliminated the excessive overtemperature on the second floor. This was clearly a benefit because the house only had one zone previously.

So, your thoughts about increasing comfort with zoning is an exercise in futility on a building with one floor with a reasonably high expense if a contractor has to do it.

If you have a room that you wish to reduce the output, just close the damper on the baseboard…………….or put some wood beneath the baseboard to reduce airflow through it………………costs you NOTHING.

Regarding a new boiler:

You are wise to consider NOTHING. If the boiler is not leaking water……………do NOT replace it. It may be fine for another 20 years.

I bought a rental house in 1986 with a Utica OBT. The boiler had to be at least 20 years old at that point. I sold that house last year and the OBT was still operating perfectly fine………….together with it's tankless coil which I NEVER replaced in 38 years. It has a 275 outdoor tank running 2 pipe with a top feed with insulated lines to and from the tank into the building. I did replace the tank once…………with another used tank. When I sold it, I promised the new owner a new Honeywell 7224 control (since the L8124 was 30 years old). Put that in for him in about one hour.

hot_rod · 1:34AM

I would definitely zone the basement if you finish that.

If you use panel radiators you can easily add TRVs for some temperature control, room by room

EBEBRATT-Ed · 2:49AM

If you only have 900 square feet of house I would only zone the basement and the house 2 zones.

Money wasted on extra zone valve, pumps etc will be a waste with a small house

Yes 3-4x the boiler cost. You probably have to :

Reline the chimney

Permits

wiring

start up and test

remove old boiler

install new

material

labor

sales tax

Flush and fill

Truck

Truck Insurance

Liability Insurance

Licenses

etc etc etc

Seeking your thoughts regarding a boiler/system upgrade for a small 1980s ranch.

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