Heat Loss Calc

Uni R_3

The Ultra 40 and Ultra 60 (same as Smart 50) only have 10 gallons diff, but the outer tank is 6 gallons vs 8 gallons of boiler water and the tappings are larger if you're piping it at 1.25" to maximize recovery. I doubt the standby loss difference between the 2 tanks is much.

As I said, my own personal preferences. I just think that it would go a bit longer between domestic calls and then run longer which is better for the boiler. Am I out to lunch?

Jimbo_5

Heat loss Calc

Recently did heat loss calcs for my house, coming up with 45K. Was figuring on an Ultra-80. But I have 2 questions you may be able to assist me with.

Firstly, how much difference will it make to my BTU needs if I add an indirect tank? Currently use a 40 gal HW tank for 2 adults and 2 teens.

Secondly, my basement is totally unheated, apx 700 sq ft. We figure that when the house was built in the 1930s they used the residual heat emitted from the boiler and exposed piping that runs throughout the basement to "heat" the basement enough to make it barely tolerable when venturing down there during winter months. I was thinking of putting a few small radiators, left over from other jobs, in the basement, on its own loop, or on a return line, just to warm the basement when I really want to. Will this dramatically alter my overall BTU needs? Any ideas? I welcom any advice or suggestions.

Uni R_3

Suggestions...

Get the 50 gallon tank instead. It holds more 33% more boiler water which will give your boiler a longer run at more than idle speed and it has 1.25" tappings in keeping with the whole low head design. You'll end up with water heating capacity that you probably never needed, but for the longer harder run times, I'd still do it (Aux tapping for recirc as well that's not on the 40).

The second one is insulate and heat the basement. Even if it is just 1" of styrofoam board that's taped and is covered with a firestop that's just tap-conned to the concrete walls. It'll make a huge difference. You won't need much heat. I believe that if you run the heatloss calcs, they'll understate the gains from insulation. Even though the walls are a sink, they are a lateral sink losing them far more than the heatloss programs I've used. Insulation makes a huge difference in a basement and the first 5Rs will make "nearly all" the difference.

Jimbo_5

Thanks, but . . .

The 50-gal tank part throws me a little. Why is the longer run time better?

Uni R_2

Just my opinion...

I think your Ultra will spend early winter and late winter and maybe even most of mid-winter on low fire. This will allow it to run a little longer at high fire (and do fewer DHW cycles).

Tony_23

Why ?

Why would you want it to run longer at high fire ?

I believe he said he's running a 40 gal gas WH now, and it's adequate. At the speed of IDWH's, in general, a 40 gallon would be more than enough. I usually install 30's for residences (including mine) and nobody runs out. In fact, the recovery rates are the same. Only the storage capacity is different, affecting the 1st hour rating. The Ultra runs on high fire for DHW every time for quick recovery.

ALH_4

idwh

The Ultra 80 will make hot water much faster than your current direct-fired water heater. The best idea is to size the boiler for the heating load, and put the indirect tank on priority. If everyone takes reasonable length reasonable flow showers, the 40gal is probably fine. I would rather have a 50 gal tank if it was me, just for the additional capacity. The price difference probably isn't much. You might plan on running it at a higher temp, such as 135°F and using a tempering valve to bring the temp down. It gives you a little more hot water and makes absolutely sure no live bacteria will remain in the tank, as they can when below 131°F.

What kind of indirect tank are you thinking of adding?

If your main floor design heat loss is 45MBH, you will have plenty of boiler left over to heat the basement if you choose in the future.

Jimbo_5

Thank you, Andrew

I was thinking of using a WM Gold Plus, probably. Though a friend of mine suggested a Maga-Stor. The house is 2 floors, apx 670 sq ft per floor, with an unfinished basement. We are definitely over-radiatored, using old cast iron rads and cast baseboard. I plan to install TRVs on all the rads and baseboard and run the circulator continously. I really don't mind hearing all the ideas offered. I want to do this right, completely, the first time. A tweak here and/or there is perfectly fine, even enjoyable. But for the most part, I'd like to have this boiler running at its optimal, if at all possible. How do you feel about the Crown Bimini?

Uni R_3

The Ultra Indirect

It matches the boiler's color if you want the right foofoo factor in the mechanical room.