Am I nuts?

gracecon1

I built a new shop. I had a professional design done for the floor. It’s installed as designed and the concrete is poured. I’m trying to decide on a boiler. I’m considering this: https://s3.amazonaws.com/s3.supplyhouse.com/product_files/Laars-JX050NPIU1-Brochure.pdf
not from here but from my local supplier.
I know it’s an 80%er, but I’ve had the older version of this boiler (jvs125) running flawlessly in my basement for 25+ years. Is it crazy to go old school? Are the wall Mount units really that much better? If so, what would you use? Plumber by trade so I can buy just about anything from the local supply houses. I had a customer who I helped limp a quietside through 10 years of constant trouble because the original installer vanished and no one else would touch it. That’s what I’m trying to avoid. Everyone is trying to sell me and I don’t know what to believe. Thanks in advance for the advice. 

EBEBRATT-Ed

two schools of thought

mod con saves on fuel because they modulate to meet the load and with a radiant system, you're in condensing mode all the time so that saves fuel. but they cost more and have a shorter life span. So it really is a mod con job. This coming from a conventional boiler guy

put in what your comfortable with

hot_rod

you would want a mixing valve and a return temperature protection method or device on a standard boiler like that. Especially when connected to a high mass distribution. Add that into the calculation

plus combustion air into the boiler location 

Is it all one zone?

gracecon1

It is one zone. Nine 260ish feet loops

EdTheHeaterMan

I had a customer with an oil fired steel boiler that was connected to a radiant floor heating system from the 1950s. The in floor tubing was 1/2" copper. Understanding all the problems with Levittown systems I was conscience of the possibility of a copper tubing failure. The customer was a young man when the slab was poured and was confident that the pipes were not leaking. Still I tested them with 25 PSI and they held for 3 days.

The boiler failed as a result of the low temperature return water and the boiler rusting thru at the flue connection after 40 years of operation.

I proposed a Crown oil fired cast iron boiler (my brand of choice) and a mixing valve to lower the water temperature. The "old school set in his ways" customer insisted that all I needed to do is connect the supply and return like the old one. I showed him the bypass piping in the new boiler instruction. He finally let me do the near boiler piping my way. He could not understand why he needed 2 circulator pumps but went along with my plan. When the old man passed away 17 years later the house was demolished and made way for new construction. So I probably could have gotten away with following his instructions.

The customer did not want Gas heat
The customer wanted to stick with Oil Heat
No other plumber wanted to deal with that copper in the slab
And the customer wanted what he wanted.

So what does this have to do with @gracecon1 being NUTS?

Just get what you are comfortable with. Remember that you will need 2 circulators and some way of mixing the hot boiler water with the lower temperature floor heat water. The simple mixing valve is the simplest method but the least accurate at offering comfort over the wide range of winter low temperatures and the seasonal fringe with milder temperatures.

Once you wrap your head around that, then I believe simple is better. You are the customer. Choose the contractor that understands radiant floor heating and that will do what you want. Operating cost savings is often absorbed by repair and maintenance of the more complicated equipment. In 20 year life of the equipment, it will be a wash. With the simple equipment, you may have 20 more years of operational life left. The ModCon will be at the end of life by that time, will you still own the building (or be alive) then?

Hot_water_fan

You’ll be making a bet on future fuel prices too, which no installer will know. If they’re feeling confident either way, then they should guarantee you a fuel price for 20 years  

EdTheHeaterMan

Hot_water_fan said:

You’ll be making a bet on future fuel prices too, which no installer will know. If they’re feeling confident either way, then they should guarantee you a fuel price for 20 years  

Almost no contractor!

This reminds me of a customer from my early days as a self employed contractor. He had an oil fired steamer that took 8 hours firing at 4.5 GPH to make enough steam to make the unit heater fans to start to blow hot air in the building. I proposed taking the oil burner out of the ash pit of the old commercial coal conversion, fabricating a new fire door that could hold the new Carlin oil burner and filling the ash pit with sand and vermiculite insulation then a layer of 2000° fire brick for the combustion chamber floor. This brought the flame up 18" higher than the old oil burner flame, and put closer to the crown sheet of the fire box where the original boiler designer wanted the coal fire to be.

The price I was asking for was less than 1/2 of a new boiler but was still a little pricy for the customer. He was not sure he believed me that I could cut 30% off of his oil consumption, so I offered him this proposal!

1. I will install all the equipment that I priced at $XXXX.xx for FREE! as long as
2. You pay me for all the oil you would use with the old burner in 5 years at what ever the current price might be. At the time the current price of 29.9 cents per gallon. That would be over 4000 gallons per winter. The price jumped to over 50 cents per gallon within the 5 years
3. I would then pay for all the oil that the new burner actually used. for the next 5 years.
4. I get to keep the difference

When he heard I was that confident of my success, He purchased the job at my proposed price.

Good thing he did. This was the most successful project I have ever done. Even I was surprised by the results. Once the burner fired up, the boiler reached 1.5 PSI steam pressure within 16 minutes and the unit heater fans started blowing warm air. Within one hour the building was at 70° (from a 40° start). Within 1.25 hours the thermostat was satisfied and shut off the burner. I did this with a 3.00 GPH nozzle at 150 PSI

Run time to get the building to temperature went from 8 hours to about 1-1/2 hours
Firing rate was changed from 4.50 GPH to about 3.50 GPH
Oil usage went from 4000 gallons per winter to less than 1000 per winter.

I would have made a killing on that job if the customer took the offer for a free burner.

hot_rod

Some of those copper tube boilers now have a primary secondary piping built in, with a circ. The manufacturers finally realized how many were going to an early grave with inadequate flow or return protection

If it is just a no frills copper tube boiler I would highly recommend two mixing valves. One to protect the boiler, one to mix.

Nicer yet is a motorized mixing valve running outdoor reset. That helps smooth out over heating the slab, and perhaps some fuel savings. Possibly even constant circulation if you take the time to dial in the reset curve.
The Taco 3 way I valve is a popular valve to accomplish your mixed temperature based on odr.