New boiler needed - suggestions on brands/BTUs?

sbug

Greetings all! Noob here. Sorry if there is a thread/discussion on boiler sizes and ideas on what to purchase.

Our Munchkin 80M finally pooped out after at least 15 (probably more like 20) years. Looking for a replacement. The space is a 1st floor apartment, about 1100 sq ft, 8 radiators (front hall, back hall, 2 bedrooms, small bath, kitchen, pantry).

2nd floor has it's own system. Basement not heated.

Any questions I should ask, brands to avoid....? BTU's for this space??

TIA for any thoughts!

Jamie Hall

Hot water heat I presume? Then the very first step is a heat loss assessment of the space to be heated. SlantFin has an excellent downloadable application for the purpose.

Then the next step is to select the correct size boiler to match that heat loss. This selection should also take into account the kind and amount of radiation you have, as you may or may not be able to use a mod/con boiler, depending on how hot the water has to be which depends on the radiation.

Then the third step is to find a really good reliable contractor. He or she will have ideas as to what makes of boiler they prefer to work with -- and it is usually best to go with those. The installer and installation quality are far more important than the boiler make and model!

JUGHNE

CI rads or baseboard convectors?
Was the 80M ModCon more than enough for the heating?
How about DHW needs?

rbeck

Consider the US Boiler K2WT which is a 10:1 turnown boiler so it will fire between 8K and 80K input. Mod-Con boilers work well in any application be it fin tube, CI radiators, radiant floor and even hydro-air. Much fuel savings in modulation.

sbug

Excellent, thanks for the thoughts, all. Gas powered, cast iron radiators. Did I mention it was a 100+ year old drafty house?

The 80M did a fine job heating the house, no problems (until it stopped working, LOL).

Probably going to go with a modulating boiler, due to the comments I've read here and elsewhere about fuel savings.

Thanks again

Ironman

Boilers with fire tube heat exchangers are generally preferred over water tube HXs.

However, the contractor is 98% of the equation. Find a COMPETENT hydronic contractor and let him install what he prefers.

Henry

We have a rule of thumb here in the Great White North. It was developed by the gas utility over several years and works well since 2000. For residential buildings with old windows, it is 3.5BTU/cu ft and 3 for new windows. I have 1600 sq ft plus a full basement and use a full modulating condensing 80,000 BTU.

Paul48

Everything you're asking is answered by having a skilled craftsman do the install. He'll have 2 things in mind......He wants you to be happy, and he wants to be happy. He'll size the boiler correctly, and select a boiler he believes to be the best quality, with the greatest available support for your area. He'll install that boiler to factory specification. He'll walk out the door with a smile, and you'll smile for years to come.

Gordy

If the 80 k munchkin served you well. Another fire tube style 80k 10:1 tdr will serve you better. 17k input was low end on the munchkin you’ll get that down to 8k with same size firetube with 10:1 tdr. Possibly Piped direct with your system.

Brands depends on what the installers find most available in your area for parts, and service.

HTP uft 80.
Lochinvar KHN

I will add there are some 5:1 tdrs with lower top end btu inputs, but you don’t gain anything on the low end of modulation, and some are not firetube heat exchangers. If an indirect for dhw is a possibility stay with the 80k

BlueGreen

What happened to the 80M that made it need to be replaced? My 140 is going on 16 years.

j a_2

Paul48 said:

Everything you're asking is answered by having a skilled craftsman do the install. He'll have 2 things in mind......He wants you to be happy, and he wants to be happy. He'll size the boiler correctly, and select a boiler he believes to be the best quality, with the greatest available support for your area. He'll install that boiler to factory specification. He'll walk out the door with a smile, and you'll smile for years to come.

Paul you sir are 100 percent correct....I hope the op listens...and follows up.

BlueGreen

If I was replacing mine today I would get the US Boiler K2WT.

Gordy

^why?

BlueGreen

Pros: 10-1, modbus, external control (0-10v would be preferred but 4-20ma conversion easy), local availability.

Cons: no top and bottom return/supply, built in circulator, combined blower/gas valve looks expensive to replace, pricey.

Maybe there is another one or two that meet those criteria.

I am not sure what current sentiment is on the Gionnani heat exchanger, but it seems pretty good.

I read the I&O of every 80k range boiler that comes out so I'll know what to get when that time comes...

Ironman

The Gianonni is an inferior design compared to a fire tube. It requires a lot more maintenance and has to have a separate high head circulator.

The HTP UFT or Lochinvar KHN are both 10 to 1 turndown with fire tube HXs.

Paul48

I thought I read that the K2 was 5 to 1?

bob eck

I believe the newer K2WT boilers are now 10-1 the old models were 5-1
Burnham now has a Aspen boiler 10-1 and it has a Fire Tube SS heat exchanger.
Lochinvar Noble 10-1 has a SS Fire Tube heat exchanger and it can also make domestic hot water. You can use the Noble combi boiler as a heating boiler only.
Lochinvar is coming out with a heat only Noble condensing gas boiler this year.
Lochinvar also has a Knight boiler with SS fire tube heat exchanger and it is a boiler only.
Weil Mclain has the Evergreen and their WM97+ condensing gas boiler with SS firetube heat exchanger
HTP also has condensing gas boilers with SS fire tube heat exchangers.
Navien has a new condensing gas boiler coming out this month with a SS fire tube heat exchanger.

Plus there are other manufacturers that build condensing gas boilers that have the SS fire tube heat exchanger in them.
That is the type of condensing boiler I would use.