Opinions on what items I will need


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Old 10-14-09, 06:24 PM
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Opinions on what items I will need

Since I just really started researching the process of installing a boiler I am just trying to get an idea of all the options there are for supplies. If you guys had your choice what would you get?
I am leaning towards a TT solo110 with a TT smart 40 Indirect DWH. The house will probably have 6 total zones. 3 for cast iron radiators on each floor, 1 for radiant in the kitchen, 1 for baseboard or radiant in the master bath, and 1 for the DHW.
Are there diff controllers I should look into to control the system or does the boiler come with an adequate enough one? Not sure about pumps, circulators, etc. Let me know what you guys would use for the install if you were able to set it up with anything you wanted. This way I can look into my options

Thanks
 
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Old 10-14-09, 09:23 PM
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What's your heatloss?

Don't count the DHW as a zone. The MCBA handles it separately already.

I'd actually go one size larger of the DHW, and then let it swing more in temperature to reduce the number of DHW cycles. Increase the differential but use something like a Taco 5000 to keep output temps flat.

Having 5 zones of heating seems excessive. My goal would be to do it with one. TRVs and FHVs can often be used even more effectively than zone controllers and multiple pumps or zone valves and t-stats. If you can do the kitchen's radiant heating with short enough tubing runs you could theoretically heat the whole house using just the internal pump. The boiler runs best direct on one zone, which only makes sense with any modcon boiler.
 
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Old 10-15-09, 04:46 AM
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heat loss was 105k. I was planning on have a zone for each floor (3) utilizing the cast iron radiators that were in the house (wife wants to keep them). there isn't any room for the cast radiators in the kitchen so I wanted to use radiant heat for that area which i would assume would have to be on a separate zone than the cast iron radiators. You think having all 3 floors one one zone is the way to go? and not to sound dumb but what are TRV's and FHV's (guessin the v stands for valve)
 
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Old 10-15-09, 04:28 PM
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They are wax powered valves. You set the temp on each rad (TRV-thermostatic radiator valves- are those nobs with the numbers on them that you see on the sides of Euro rads). FHVs are the same things but for FH-floor heating. Danfoss and other companies make them.

The kitchen may actually not need any emitters depending on the design. How would you do the radiant?
 
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Old 10-15-09, 04:54 PM
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(not an expert)

I certainly see some advantages to having each floor on a separate zone. You can have a thermostat on each floor that would help keep the house more evenly heated. With the thermostat you will be able to adjust the automatically every day for when you go to work or to sleep. I don't know what the usage is for each of your floors, but if you find yourself not living on one floor very often, you can keep it set at a lower temp than the rest of the house for the times you aren't there. If you use those thermostatic valves on each rad, you would have to run around to every rad to do those types of adjustments. Just my 2 cents.
 
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Old 10-15-09, 05:06 PM
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haven't figured out the radiant for the kitchen yet. it will have to go between the joists as the sub floor is already in. the finished floor will be strand bamboo.
I like the idea of zones on each floor as well but dont want the boiler short cycling. I almost like the idea of having the controls on each radiator (kinda like having a zone for each room then) kinda wonderin how they actually work though. also for the radiant wont I need a lower water temp than i do for the Cast iron rads.
 
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Old 10-15-09, 05:30 PM
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With an outdoor reset, you shouldn't have a problem with short cycling.
 
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Old 10-15-09, 05:53 PM
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Originally Posted by drooplug View Post
With an outdoor reset, you shouldn't have a problem with short cycling.
Why is that?


......................................
 
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Old 10-15-09, 05:55 PM
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Originally Posted by dings View Post
I almost like the idea of having the controls on each radiator (kinda like having a zone for each room then) kinda wonderin how they actually work though. also for the radiant wont I need a lower water temp than i do for the Cast iron rads.
TRVs are an ancient, tried and true technology.

You may or may not need a different water temperature for the floor. It depends on the load calculations, type of radiant, floor area available for output, etc. etc. In other words, do your homework and you'll get the answer.
 
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Old 10-15-09, 06:00 PM
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If you go with 3 or more zones, you might consider a buffer tank to mitigate short-cycling. The 110 will only modulate down to about 30k or so, and chances are the zones will not be synchronous, or near a load above the minimum a good percentage of the time. There are a bunch of off-the-shelf buffers these days, like Boiler Buddy, or any of the HTP Superstor indirects come in a -B flavor that is a 4-port buffer tank. Heat-Flo makes 'em too.

Buffer tank sizing is pretty simple:

Vbt = t(Qh - qload) / (500 * dT)

where

Vbt size of buffer (gal)
t desired on-cycle (min)
Qh energy source output (BTU/hr)
qload rate of heat extraction from buffer (BTU/hr)
dT temp rise of tank between on/off cycles (F)
 
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Old 10-15-09, 06:02 PM
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I don't understand how outdoor reset stops short cycling. Depending on the design water temp on the radiant it may be no lower then the cast iron rads zones. Cast iron rads will work well at low water temps. How did you do the heat loss. Unless the home is 3000 sq ft sounds large. What water temp is required for your radiant heat? Then divide the sq ft of cast iron radiation into the heat loss and determine the water temp required. I hope you also did the heat loss at 60f also.
See link
Outdoor Reset Explained
and this for your proper outdoor design temperatures to verify you used the right one.
Multiple_boiler Installation
 
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Old 10-15-09, 06:06 PM
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I managed to combine underflloor pex-al-pex and plates in the kitchen and the baths with monoflo piped fintube in the rest of the house. There are simple tools out there to help with the math. The math needs to be close but not perfect. I did the loops all fairly short to match the rest of the system. The crippleware CD that came with Modern Hydronics helped, as did SlantFin's now discontinued Hydronic Explorer.

I never did fully calculate the pumping because of it being monoflo.

That was all driven by just the internal pump on the Solo 110. The monoflo dictated speed 2 even without any of the radiant since it needs velocity to work.
 
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Old 10-15-09, 06:23 PM
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heat loss was done by a plumbing supply company. I wasnt there when they did it so I dont know exactly how they came up with the numbers. House is around 2500sq ft.
The Boiler will be installed right under the kitchen area so the runs to the floor will be the shortest in the setup. I will be using pex for the radiant but havent yet really researched my options in setup for that yet.
Lots of info to process. keep it coming
 
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Old 10-15-09, 06:25 PM
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Originally Posted by xiphias View Post
The 110 will only modulate down to about 30k or so...
More like in the 38 MBH (input) range based on my experience and feedback from others who clocked their boilers.

That said, the only time the boiler will short cycle is if it has a ridiculously small load. My kitchen was 2 90' 1/2" PAP loops. If I had only one loop open and absolutely everything else closed I could get it to short cycle - 3 minutes firings instead of the regular 10 minute firings. The boiler typically fires 10 minutes at a time, until it is cold enough for it to modulate continuously. For me that was at very cold temps.

Between the MCBA's logic and the 2.5 gallon heat exchanger I wouldn't bother with a buffer tank. I put one on mine but it was to increase the ΔT for better condensing because the monoflo requires the water be pumped faster than what normally would be ideal. It lowered the return temps by 2* since it was spreading the BTUs over 46 more gallons.

If you want 30 MBH out of a Prestige 110, you would have to lower the minimum fan speed from 1900 rpm to 1500 rpm and Triangle-Tube would frown heavily on that. There is an OEM level parameter that is set at the factory that won't permit the boiler to go any slower than 1500. Why this isn't 1900 rpm is beyond me. The same model boiler is Europe (parent company is ACV of Belgium) modulates down to around 20 MBH.
 
 

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