Time to pull the trigger

tiredofchoppingwood

electric!

I didn't even consider electric. Though at first guess I am going to say it is less cost effective where I am at. I don't know anyone who uses electric for a boiler or hot water tank. I can't even say I have ever seen one before actually.



I will look for the numbers.



Thanks.

RobG

Fun

This is certainly a fun thread! TOCW are you a comedian for a living there in the upper east? I agree Weezbo makes for a tough but informative read (I have often wondered what his electronic signature meant as well). What are your KW rates and what is the cost of LP? Electricity is 100% efficient BUT it all comes down to dollars and cents. Is natural gas a future possibility?  



Rob

tiredofchoppingwood

About

9 cents a KWh, but I see it go upwards of 12 cents on any given month.

Natural gas isn't close enough to me at the moment, but it might one day I suppose.

LP is running high at the moment at around 85 cents a litre. Something like 3.40 -ish a gallon I guess. Sorry, I am a child of the 70's in canada. I am caught between measurement systems.

tiredofchoppingwood

correction

I just called the propane guys for todays number and it is 52 cents a litre.

So 2.10 ish a gallon.

I should fill my tank up while the getting is good!

RobG

My god man!

Buy the propane!! I wish that I could get it at that price.

Gordy

Weezbos emoji

Is him in a stocking hat ensemble . It's cold up there.

RobG

I see it now!

Thanks Gordy, If I turn my computer ninety degrees clockwise it all makes sense! Smiley face and a stocking cap with a little ball on top. Thank you for finally giving an answer to the age old question "What the hell is that"



Regards,

Rob

Gordy

Saman

Maybe I'm missing something but if your piping P/S , or using a low loss header you would need two SS circs. If you use a HX you would need one SS circ on the heating side and a Ci on the boiler side. If you pipe direct then one ss circ but with that boiler HX should be a fore mentioned piping I think ops flow right will be different than minimum boiler flow rate.

RobG

Gordy

I think that you misread Carl's thread. The only upgrade needed for piping without a HE would be a stainless circ.

As well, I can't imagine the price of a stainless or bronze low loss header. I would go with the closely spaced tees.



Rob

Zman

Circ

Gordy,

What I was trying to say is that in either design you need one stainless circ and expansion tank.

The only price increase by going without the the HX is an additional SS circ.

If you go with the exchanger, you need the other stuff as well.

Yes 2 stainless circs total without the exchanger.

Carl

tiredofchoppingwood

You're Right!

It is a guy in what we call a toque in canada. I totally see it now.

It's like that moment when you are standing in front of one of those patterns at the mall, then all of a sudden a boat with unicorns dancing in the sky appears from the pattern.



On a completely Weezbo unrelated question:



I take it the expansion tank will need to be one normally used in potable systems?

Does it have to be stainless or can it be lined?



Also, looking at the wiring diagrams for the cadet, I am guessing I get a thermostat and wire it to a relay for the pump(s). Can a single relay control two pumps?

tiredofchoppingwood

DUH!

Never mind the last question. Of course a single relay can trigger multiple pumps.



It just needed to simmer in my luke warm skull for a little bit.

Zman

Simmer

the tank should be designed for potable water. Make sure you reduce the pressure before you install it.(usually 15#)

The boiler could control both circs as well, as long as they are less than 1.8 amp combined.(they are)

If you are doing a fancy t-stat that needs a common the relay is a good idea.

Why not at least have the boiler control the boiler circ?

Carl

Gordy

Sorry Carl

For the misspell, and misread post. Understand.

tiredofchoppingwood

well cooked

Okay, so the cadet can trigger both pumps you say?

The manual does a crummy job of dealing with this topic.



But that's fine. I'll suss it out.



Thanks.

SWEI

You can sometimes pump the Cadet directly

especially on a low load system.  Trust the math.

tiredofchoppingwood

That would be cool

If I understand you correctly that is.



Do you mean to say I might be able to have no P/S, no Hydro separator and just one pump?

Cause that would be great!

How does the math go on that?

You don't need to do it for me, just let me know how I figure it out or a link to a clear explanation of how I make that calculation.

SWEI

Math

is all about flow rates and ∆T.  As long as you can move enough water through the HX and the emitter system at design conditions you are good.  The Cadet uses a Giannoni HX, which has relatively high head loss.  See p. 38 in the Installation & Service Manual and remember that your maximum load for heating is less than the boiler maximum capacity.  I don't recall whether the Cadet controls include a maximum firing rate limitation or not, but that would potentially allow you even more flexibility with the flow rate (assuming there's no indirect water heater, which will want all the BTUs you can give it.)



HOWEVER, with an RFH application you're going to have a conflict between the low ∆T the floor needs and the high ∆T the boiler is likely to end up with due to the HX restriction.  If you end up needing primary/secondary piping, consider the little B&G ecocirc e3 Vario as a primary pump.  It works quite well with the CDN040 in that application -- everything else I've seen overpumps, producing a low ∆T.

tiredofchoppingwood

hmmm

Okay, so thats interesting.

So How do I figure that out?

what I know is this:



4 circuits.

One zone.

235' is the longest circuit, but they are all pretty close to the same length from the notes I was given.

design loss is somewhere in the 19k to 24k.

(24k is just a conservative guess in case the insulation isn't all that or who knows what? 19k is the number I came up with when I did all the calculations though)

What else?

No indirect HWT, just the slab.



Thanks

tiredofchoppingwood

loose

calculation, if I have this at all right.

is a head loss of somewhere around 8, but I could have the formula completely wrong.

So if this is correct, I see from the chart on pg 38 that this falls in the range of the Cadet 40 with a gpm of 3.5-ish. Am I getting this right?

Gordy

Playing with the math

Direct connection to the cadet is doable in your case. What it boils down to is your selection of delta t, and btu load you decide to use. At 24k heat loss with a 15* delta on the emitter puts flow rate around .8 gpm per loop for total of 3.2 gpm, and 4.7 feet of head in the emitter end plus cadet head loss of around 4 so you are close. This will give a nice delta for the boiler.



If you want a narrower delta on the floor flow rates go up along with head, pump size, and narrower delta at boiler.

tiredofchoppingwood

Cool.

so does doable mean it will be maybe, kinda ok or does doable mean it will work?



I guess if out doesn't work, it's not too hard to repipe it as P/S etc.



Thanks

Gordy

Doable

The head of the emitter side, and the boiler side are not added together like my previous post sounds to indicate, so your around 4.7' of head total. You could tighten up the delta on the emitter end to 10 or 12 degrees, but that increases pump head by double, and may be out of the Viro pump curve. Maybe Kurt has a different option.



IF your heat loss is less than 24K then you could drop your same flow rate, and narrow your delta, and still be in that 5' of head range. say 20 21K.

SWEI

The heads do add

if they are in series with a single pump, no?

Gordy

Kurt is Right

They are added. Sorry the P/S side of my brain tried to over take the direct connect side.

Rich_49

Hate

when that happens Gordy . Happens more often now as we move past P/S pipng .

tiredofchoppingwood

I'll give it a shot!

I placed the order for the boiler...fingers crossed!



Thanks everyone!