What is a good new replacement for a Dunkirk 35 yr old boiler?

itguy

I am new to this forum... I decided to get a new boiler because this spring because I think it is time even though the my 35 year old gas boiler Dunkirk PVW1125 90000 BTU (Input 112500) is still running. Unfortunately I don't know where to start and what to get. I care most abut the reliability (like the one I have). I also care about small foot print size (Dunkirk is only 14" x 19" excluding attachments like water pump, gas pump, etc.) due to small enclosed area available. I don't care about the efficiency as long as it is not rated less than what I have (I think Dunkirk is about 75%). My boiler vents to a roof-top chimney. My house is a raise ranch with finished downstairs (about 1900sf living space) with two thermostats and baseboard radiators. I would appreciate any suggestions as I am not familiar with current popular gas boilers.

Jamie Hall

Hot water? I presume. There are a number of quality boilers available -- and they will all be much higher efficiency than what you have now, and likely smaller. They also won't last as long.

That said, however, the first step is to either do, or have done, a real heat loss assessment of your house. The existing boiler may or may not be the right size, but you can't guess on this. To get the performance you pay for from a new boiler, it has to be sized to the reality of the house, not what was there before.

Which leads to the second essential: select a contractor who knows hot water heat and has an excellent reputation. Boilers are not plug and play, and a poor installation can make even the best boiler made into a real loser. This contractor will do the heat loss calculation mentioned above (if they don't, or says something like we'll go with what you have, or something like well in this area we figure on X BTUh per square foot, they're not who you want). They will also almost certainly have one or two makes of boilers with which they are familiar and comfortable. If the contractor is good, go with that (just as with cars: you wouldn't ask a Chevy dealer to sell you a Honda...).

itguy

Thanks for the input. I have been been very happy with the heating of the house even at below zero temperatures outside (I am in CT) level and my gas bill. Why shouldn't I have the same BTU boiler as now and not go through heat loss calculation stuff and just fine one of the best 90000 BTU boiler out there with the correct foot-print size,

pecmsg

When that boiler was installed oil and gas were cheap. It was common to over size by 50 - 150%. 

Get it sized properly!

bburd

A correctly sized boiler will cost less to install and to operate.

MaxMercy

itguy said:

Why shouldn't I have the same BTU boiler as now and not go through heat loss calculation stuff and just fine one of the best 90000 BTU boiler out there with the correct foot-print size,

I did what you're suggesting. I'm in CT and replaced my 154K BTU boiler with another of the same size (house about 2800sq 2X6 insulated walls and double pane windows).

I installed my boiler three years ago copying what was there and trouble free for 30 years, and I find my boiler is short cycling even in cold weather. My boiler is clearly oversized even though I'm firing it at 0.85gph (oil burner - lowest suggested firing rate).

I wish I had joined here earlier and did the heat load calculations that you are being advised to do. My original boiler was oversized, and my three year old boiler is as well.

You may very well be sized properly, but spending a little bit of time to replace something that should last 20-30 years is time wells spent, even if the result is to keep the size you are using now.

EBEBRATT-Ed

@itguy

Check find a contractor on this site. Maybe you can get @Charlie from wmass

Gilmorrie

35 years is not all that old for a boiler that is running reliably (mine is 70). I would save your money. Don't believe any boiler salesman that tries to sell you on the basis of higher efficiency and fuel cost savings. The payback period will not economically justify the cost of replacing a boiler that works reliably.

Gilmorrie

P.S. The lifetime of a hot-water boiler is generally the time until it splits open and leaks. Your existing 35-y/o Dunkirk may have more life remaining than a new boiler you replace it with.

JUGHNE

If your boiler is not oversized then on the coldest typical day you have the fire should run continuously to get you thru those few days. The rest of the year it is too big and will cycle on and off.
Most efficiency comes from less cycling and longer life with fewer starts.

HVACNUT

@itguy, the heat loss calculation is the job of the contractor, not yours.  
A boiler with a net of 50K BTU is still almost 29 BTU per square foot, and that's still ridiculously high for your 1900 sq ft, I don't care where you live.
Weil McLain, Peerless, Burnham, are some American companies you can look into for an atmospheric boiler. 
What makes domestic hot water?
If it's an exterior chimney and doesn't yet have a stainless liner, that's going to be a must. 

HVACNUT

Gilmorrie said:

P.S. The lifetime of a hot-water boiler is generally the time until it splits open and leaks. Your existing 35-y/o Dunkirk may have more life remaining than a new boiler you replace it with.

The block is just one component. A gas valve here, a circulator there, a switching relay next year. How far does it go just because the block is good? 
It's not just a boiler replacement, but a complete system upgrade. All new from the ceiling down to the floor. A buck gets ten the OP's existing setup is not pumping away. 
And it's not always about return on investment, it's about peace of mind. 

itguy

Thanks for comments and suggestions. Now, I am a bit confused. I need to digest all this. I am just an IT guy who doesn't know anything about this boiler stuff, but I am very willing to learn. Last week I had the water pump (Grundfos UP 15-42F) replaced because it had started making some noise when it was running, not very loud, just enough to wake me up (bedroom is just above the boiler room). It had never made any audible noise in the past even when you placed your ears right next to it. This was the reason why I started thinking about replacing the boiler with a new one.

The CNG guy put in a new TACO pump. As soon as he turned the system back on, this new pump was making the similar noise like the old Grundfos pump, but not as loud. Fortunately, the noise level is not waking me up. However, there was one more issue when he was here. After he turned the shut-off valves back on most of them started to leak water for a while and they stopped leaking. He said this was normal for valves that were not used for several years. Unfortunately, I noticed that one of the shut-off valves is still leaking some water when the water pump is NOT running (couple drops every minute). My question: Will this stop in the near future? I remember one of my sink shut-off valves leaked water for couple weeks and it stopped few years back. Meantime, will the loss of water due to leak cause any problems with the heating system? Should I call the CNG and have them fix the leak immediately or should I wait a while to see if the leak will stop?

HVACNUT

It could be just a packing nut needs tightening, or it could be a can of worms. 
Wipe the valve dry and see where its leaking from. If it's from the nut behind the handle, just snug it up until it stops. But don't go gorilla on it and snap it. That's when the worms come. BTW, a new system comes with new valves. 

iPipefitter

I would have the contractor do a BTU calculation of the house to tell you what size boiler you will need. Then they should do all the heavy lifting when it comes to finding you a correct size boiler/heating system needed for what you need. Also, a poorly insulated room will require more BTU's to heat the room, so keep this in mind as it is an older house and probably doesn't have the best insulation.

BrassFinger

HVACNUT said:

@itguy, the heat loss calculation is the job of the contractor, not yours.  
A boiler with a net of 50K BTU is still almost 29 BTU per square foot, and that's still ridiculously high for your 1900 sq ft, I don't care where you live.

I wish the contractor had performed a heat loss calc on my home when the furnace and A/C were replaced during a 2001 remodel (I purchased the home 4 years ago). 1969 home, 1800 sq. ft. CapeCod style. Total gut-job remodel, new windows, etc. in 2001, insulation still 1969 level.

Furnace is a 110K BTU (!!!!!!!!!) input 80% Carrier and the A/C is a 3 ton 10 SEER. Pretty generic but WAY oversized on both. We had -12F here in N. Central Illinois Saturday night and a high of 2 yesterday and the furnace was at most running an average 55% duty cycle to maintain 67-68 indoor. The A/C is similarly oversized with much shade from trees. An 80K/80% with 2-tons, at most 2-1/2 would likely be more than enough. I realize there needs to be a little buffer for the "worst case" scenarios but a few years ago we had a morning with -37F and I don't think the furnace even noticed. I run the thermostat at a 2 degree differential to minimize the short cycling with only a small decrease in comfort.

ethicalpaul

Last week I had the water pump (Grundfos UP 15-42F) replaced because it had started making some noise when it was running, not very loud, just enough to wake me up (bedroom is just above the boiler room). It had never made any audible noise in the past even when you placed your ears right next to it. This was the reason why I started thinking about replacing the boiler with a new one.

As a fellow IT guy, let me tell you that thinking about replacing your boiler because a pump starts making noise is akin to replacing your computer because your mouse stopped working.

STEAM DOCTOR

Even replacing the pump may have been unnecessary. The noice may have been from air in the system.