Weil McLain Ultra Series 1

[Hareboy]

Do you have experience with the series 1?
Long story kind of short… I have a waste oil boiler, I want to parallel it with a gas boiler. Looking at used Weil-McLain Ultra units. Engineer calculated my boiler size to be 225,000. I can get a deal on an Ultra 300.
Will this work for me? Will it modulate low enough to be efficient? Can it be set to a max firing rate lower than 300000 btu?

[beenthere]

Do you have experience with the series 1?
Long story kind of short… I have a waste oil boiler, I want to parallel it with a gas boiler. Looking at used Weil-McLain Ultra units. Engineer calculated my boiler size to be 225,000. I can get a deal on an Ultra 300.
Will this work for me? Will it modulate low enough to be efficient? Can it be set to a max firing rate lower than 300000 btu?

Yes it can be set to a max firing rate. However, getting the right size would be far more efficient.

Just because you have a 225,000 now, doesn't mean you need one that large. Very possible you would only need an Ultra 155, which can modulate down to 31,000 BTUs input, instead of the 62,000 of the 310.

The actual model would be a Ultra 310.

[Hareboy]

Thanks for the reply, as you might assume, i am eager to proceed (cold weather). I can also get a deal on a 105,000, I will check into. Are there any things/problem areas to look for on a used Ultra?

[qwerty hvac]

Yes, why are they used in the first place? People don't spend that type of money on a piece of equipment to take it out and replace it with something else. Parts for these are on the high end.

Thanks for the reply, as you might assume, i am eager to proceed (cold weather). I can also get a deal on a 105,000, I will check into. Are there any things/problem areas to look for on a used Ultra?

[beenthere]

As above. Find out why they were removed.

Then do a heat loss calc on your house to find out what size boiler you really need.

[Hareboy]

Both were remodles of some sort, I know these are pricey, I am also suspect, thats why I am asking you. The 300000, was a convert to forced air, the other said they took down the house.

[skippedover]

Is this a residential project? Very large home?

[Hareboy]

yes, my home, 4000+ sq feet/ garage/ basement

[beenthere]

yes, my home, 4000+ sq feet/ garage/ basement

I have a 250 doing an office building that has 5600 sq ft. The 250 is slightly over sized, but a 155 was a tad too small.

[Hareboy]

in your opinion, would a 300000, or a 105000 be better? assuming the cost is the same.

[bob_scheel]

in your opinion, would a 300000, or a 105000 be better? assuming the cost is the same.

You need a load calc done to determine what the minimum size is. It is better to have a smaller unit IF it is adequate to meet the load because it can throttle down lower and run more efficiently in milder weather which is 80% of your run time. It is pretty common to see older units way oversized, especially as people have invested in more efficient insulation, windows, and doors. Another factor is that you old unit probably drew its combustion air from the inside of the house. Cold outdoor air has to infiltrate to replace this air. The ultra and most new high efficiency units draw their combustion air directly from the outside and save some more btus that way.

[beenthere]

As above. A load calc to determine proper size. Proper size will get you the m ost out of a condensing boiler.

[Hareboy]

House is new 2 years old, boiler is in seperate room, in garage. So I would guess 225,000 is a fair calculation. with that said, do you think 300,000 is far too big? ans what to look for on used boilers.