crown boiler bimini

Paul S_3

Will be installing a crown boiler bimini next week (BWC120]...heat load of home is 118,000 btus.. My question is there are a few options regarding the boiler loop in gpm....since the heat load is 120,000 BTUs do I use the 12 gpm option with the 0013 taco circulator?....and cab I use a taco iseries mixing valve (3way) with this boiler? Thanks Paul s

Zman

More info

What do you mean by heat load? Where did the number come from?

Have you done a heat loss calc?

What would the mixing valve be used for?

How big is the house? What type of radiation?

Carl

Paul S_3

heat loss

the heat loss calculation of the home I have done it on a computer program called slant fun heat loss express...also I used the uponor radiant heating program for the first floor which had radiant heating buried in concrete....sadly enough the contractor installed all the radiation in home....2nd floor and attic have baseboard heat 3/4"baseline 2000....home is about 3000 sq ft give or take....I want to use the iseries fit the radiant...and they also ran snowmelt...which I would use a heat exchanger....driveway is 20x40....contractor used 3 loops of 3/4" pex for the snowmelt all about 200 ft in length....contractor ignored my snow melt design and ran pex in a serpentine patern....I cannot pick my jobs with this guy...I have to make my side of work add professional as I can with what I have to work with thanks Paul s

Paul S_3

snowmelt

I'm thinking on using the tekmar 667 snow melt control for this job of contractor allows for it...

Zman

Boiler

The crown boiler has very few control options.

Why did the contractor buy a condensing boiler? You are going to be forced to run it high temp most of the time in order to make the baseboards work. Normally, I would suggest a tekmar setup. The boiler does not take 0-10 vdc input so that will not work.

Unless you get creative with the snowmelt controls, the boiler is going to fall flat on it's face when the outdoor slab comes on line. A 667 will help as you can regulate the delta t and boiler minimum temps.

If he won't spring for 667, you could put an aqua stat on the boiler loop so that the snow melt will turn on only when the boiler is keeping up.

Yes you can use an I mix valve. I don't see why you can't use the 0014 circ the manual calls for.

Be careful how you control the snowmelt. If the snowmelt circ runs without the boiler circ, the exchanger will turn to a block of ice. Don't ask how I know that, let's just say " I heard about a guy...."

As you know, this would be much easier with a proper design from the beginning.

Carl

Paul S_3

Carl

correct me if I'm wrong but 120000 BTU requires 12 gallons per minute with a 20 degree temperature difference?....if I use the 0014 I only get 8 gallons per minute.... and in the boiler manual it says if the flow in the primary Loop is greater than the flow and the secondary loop I could never get 180 degree water. I know this is another job that I have to work with what I got. the reason why the contractor bought a condensing boiler was because he thinks it's going to be very efficient. but that's not the case if the water temp is very high it would never condense? Thanks for help Paul s

Zman

Delta T

120,000 is the input BTU rating. In a high temp application the boiler will likely burn at 84%. That would give you an output of 100,800.

The head loss in the manual gives a very generous boiler piping allowance. I think most installations will use less piping.

There is no reason you have to be at a 20 degree delta at full fire. I would not design for perfection on the coldest day at the expense of over pumping on your typical heating day.

A condensing boiler will have the same combustion efficiency as a conventional boiler at 180 degrees. The overall efficiency will likely be higher because the turn down ratio will reduce short cycling.



Carl