Mod-Con boiler with DHW ?
Hello. I am in the process of building a new house. Ranch style, radiant floor heat in basement and main floor. I have done alot of research on modulating condensing boilers and plan to purchase one. I'm leaning towards the Triangle Tube Prestige with either their indirect tank or a SuperStor. The heat loss/load calculation shows 63,000 btu. So, a Prestige at 100,000 btu would be plenty, and I'm sure enough for the added load of the indirect tank. My question is whether I would be better off with a smaller boiler from a different manufacturer. Would an 80,000 btu take care of the house load and the indirect hot water tank?
More questions, variable speed injection, mixing valves....
Hello again. I will be using a properly sized condensing boiler with an indirect hot water tank. Now my issue involves the different temperature requirements of two different radiant applications. In a house I built 9 years ago, I just used a Slant Fin direct-vent cast iron boiler with two manual mixing valves to mix down the temperature for the basement concrete slab and the under-subfloor heat. No outdoor reset, just two thermostats. Did run the boiler at only 160 degrees, always had plenty of heat.
With my new system, I want to take full advantage of outdoor reset and lowest possible boiler temperatures. With manual mixing valves, the temp in the loops won't go down, unless of course the boiler temp goes below the setting of the mixing valve. To do it correctly, I find that I will need a mixing solution that will also take advantage of outdoor reset. As I see it, the best way is to have two seperate injection pumps or two controllable mixing valves for the two different temperatures required. Am I correct? Any other suggestions? I am finding that the controls for dual injection systems can be quite expensive, 30 to 50 percent the cost of the boiler. Many condensing boilers have outdoor reset and DHW priority built-in. What I don't find is variable injection control. Any boilers have that?
Thanks for any help,