Replacement for 1960's era N.G. boiler....

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NY_Rob

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Thanks Leon... I had hoped the control systems were smarter than that by now.

Maybe I should go with zoning with two circulators (vs. one circulator with two zone valves) because my two zones are so different and use on of the variable speed adjustable circulators to get each zone dialed in properly?
http://www.taco-hvac.com/products/variable_speed_products/viridian_vr1816/index.html#

Currently I use a Taco 007 on each of the two zones with my cast iron boiler.
 
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Leon82

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That one has pressure modes so one may be just fine. You would need to run the math to be sure
 

Dana

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Setting a smart pump up for delta-T mode on a direct pumped mod-con boiler would usually be a mistake. The constant pressure approach should work pretty well with three parallel zones and zone valves, and would use 10% of the electricity of a manifold-full of Taco 007s. With a cast-iron boiler the 007s are fine due to the low duty cycle of operation, but when you dial in a mod-con the pumps would run almost continuously (and with the Taco-007s, at a very low delta-T when operating at condensing temps.)
 

NY_Rob

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Hopefully I got this right.....
Pump Pressure in Feet of Head = Feet of Pipe x 1.5 x .04.

-So for my 170ft long zone:
170'*1.5*.04=10.2ft head
-For my 80k output UFT boiler at a flow rate of 8GPM according to it's pressure drop chart has a 3 ft head pressure drop.
Piping loss 10.2 ft + Boiler loss 3 ft = 13.2 Ft Head loss for zone one

I'll have to measure the other two loops that run in parallel that make up zone two.
Assuming the two loops are close in total length- do I take the average of the two loops and use that for head loss calculations?
 
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NY_Rob

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Setting a smart pump up for delta-T mode on a direct pumped mod-con boiler would usually be a mistake. The constant pressure approach should work pretty well with three parallel zones and zone valves, and would use 10% of the electricity of a manifold-full of Taco 007s. With a cast-iron boiler the 007s are fine due to the low duty cycle of operation, but when you dial in a mod-con the pumps would run almost continuously (and with the Taco-007s, at a very low delta-T when operating at condensing temps.)
Thanks Dana,
I'm very interested in a one time investment in the ECM circulators even at double the price of the old 007 series if it will result in an 85% electric savings. Thanks to the helpful folks here I now realize that the mod-cons could be circulating 20+ hrs/day so that energy usage on the old split cap circulators like the 007/008 could really add up.

Here's the TACO VR1816 ECM in Constant Pressure Mode:
TACO VR1816 ECM in Constant Pressure Mode.jpg
 

John Molyneux

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Setting a smart pump up for delta-T mode on a direct pumped mod-con boiler would usually be a mistake. The constant pressure approach should work pretty well with three parallel zones and zone valves, and would use 10% of the electricity of a manifold-full of Taco 007s. With a cast-iron boiler the 007s are fine due to the low duty cycle of operation, but when you dial in a mod-con the pumps would run almost continuously (and with the Taco-007s, at a very low delta-T when operating at condensing temps.)

Would it be worth it and/or possible to replace a standard 3-speed internal boiler circ pump with an ecm version?
 

NY_Rob

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I now have measured all three heating loops in my system, how would I go about calculating if the TACO VR1816 ECM pump would be able to work as the only circulator in my system (zoning with zone valves)? I will use a separate small circulator for the indirect DHW heater.
I have:
Zone one- one 160' 3/4" copper loop with 43' of fin.
Zone two- two loops in parallel, one 152' 3/4" copper loop with 46' of fin, the other loop 115' 3/4" copper loop with 52 of fin.

Thanks!
 

NY_Rob

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Update...
Spoke with tech support at Taco... gave them all pertinent info including loop lengths/fin lengths, new boiler type/size/TDR, heat loss calculation, current circulator setup (2x Taco 007's), etc...
He had no hesitation recommending going with a single energy efficient TACO VR1816 ECM pump (set in constant pressure mode) and zone valves.

So that's a few more pieces of the puzzle put into place:
HTP/Westinghouse UFT-80W Mod/Con boiler
TACO VR1816 ECM circulator pump
(2x) Taco Zone Sentry Valves (4-wire)


For the Indirect DHW Heater I'm leaning towards the HTP SuperStore Ultra (SS tank, no anode rod, 1" boiler connections, 6ft head)
For the indirect circulator I'm considering the Honeywell PC3F1558IUF00 -AquaPUMP Hydronic 3-Speed Circulator Pump

Still have to decide on direct side vent or use current chimney as a chase for the exhaust venting with a 3" chimney kit..
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FWIW- Taco support also told me they will be introducing an energy efficient single speed ECM version of the best selling 007 circulator.
 

Dana

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BTW: It appears that HTP (and several other companies' combi boilers) are the Kiturami Homsys under the tin:


19408_CA01_SUB.jpg


It looks like HTP was importing far more than just the heat exchanger! (Can't keep a good design down, I guess!)

Looks like the Korean competition for the North American market is warming up- Navien is a trademark for Kyung Dong Boiler. I'm liking Kiturami's fire-tube heat exchanger approach better than Navien's dual finned water tube heat exchangers on their boilers.
 

NY_Rob

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^ interesting..... the plot thickens!
Unless something unforeseen happens- I'm still pretty much set on the HTP/Westinghouse UFT.
Looking at the control board of the Korean boiler- it has a few less features (no night setback for space heating/DHW, no smartphone app, no three color display, only one vs. three T/T contacts, etc) than the Lochinvar- but at less than half the price- I can scrape by without those features. I could literally buy a whole second Westinghouse UFT and keep it in storage for parts and still be a tad under the price for the Lochinvar.
And... the HTP/Westinghouse is direct piped so no boiler pump, less electric use, fewer moving parts- and simpler near boiler piping.
 

NY_Rob

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Back with more questions....:D

Looking for opinions/recommendations regarding zoning for the new mod/con boiler...

I have three copper baseboard loops in the house:
Upstairs 142' loop, 46' fin baseboard- 9.1ft head
Downstairs 115' loop, 52' fin baseboard- 6.9ft head
Apartment 160' loop, 43' fin baseboard- 9.6ft head

-Currently Upstairs and Downstairs loops have their returns joined together into one 007 circulator controlled by one thermostat in-between the first and second floors. Since the loops are different lengths- flow volume is controlled via a gate valve on each loop- one valve is opened xx turns, the other valve is opened xx turns to achieve even heat from the upstairs and downstairs loops through the one 007 circulator pump.
-The Apartment loop has it's own 007 circulator and thermostat.

With the new boiler I'd like to go with just one Delta P system pump (Taco VR1816 or Grundfos ALPHA 15-55 F) and zone valves for the two zones.
But... I'm wondering if the boiler and Delta P pump (in constant pressure mode) would be better off with the current setup of upstairs and downstairs in parallel off one zone valve and the apartment loop on the second zone valve or would it be more efficient/more comfortable breaking the system into three zones? I now have the perfect opportunity to separate the upstairs and downstairs loops since all the near boiler plumbing has to go. So I'm wondering if it's worthwhile to add an upstairs thermostat and zone valve and just have three zones or keep the piping/zoning as is with two zones?

As always thanks for any advise offered!
 

Leon82

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Both those zones are bigger than the apartment zone so it won't be as bad as breaking into very small zone.
 

NY_Rob

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Thanks Leon,

The way I'm looking at is currently I have one larger zone (46' + 52' baseboard in parallel) and one small zone (43' baseboard)- to me that seems way unbalanced. If I break it back to three zones- they, be much closer in fin length (43', 46', 52') to each-other which would make the heating load between the zones much more even and give the boiler and Delta P pump a chance to function properly.
 
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Beads

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I am chiming in with a couple of late comments.


At the beginning of the thread there was discussion about two boilers that have different high end capacity, but modulate back to about the same capacity. The question was whether there is any disadvantage to buying the higher capacity. I don’ t know if all boilers go to highest capacity and then modulate back, For those that do, I read a study that might be enlightening. It has real fuel us data and compared the same system with the highest firing locked out and with that available. The highest fire locked out mode resulted in lower fuel use and heated the home just fine.

The effectiveness of set backs for efficiency depend on factors including the rate of heat loss for the structure and the difference in efficiency in full-throttle operation vs. lower output. There is no way you can say that a system is running with less fuel without set backs without empirical data or a lot of calculations which might require data that you can’t get from the manufacturers. If said manufacturers provided a set back recovery mode vs. making you use the flat out 100% output, anyone could use set backs efficiently. I believe that some boilers can approach that if you tweak the settings, but I’ve not seen any discussion of links to better thermostats that would allow them to distinguish a set back from a deficit.
 

Leon82

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My last gas bill I averaged 1 ccf less than last year and it was 1 degree warmer last year.
I don't use a set back and have limited the boiler to 60 percent output.

with a mod con the setbach should be controlled by the boiler, not the thermostat


N0w that the boiler is closer to the heat loss it will take longer to recover from a setback also.
 

NY_Rob

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At the beginning of the thread there was discussion about two boilers that have different high end capacity, but modulate back to about the same capacity. The question was whether there is any disadvantage to buying the higher capacity. I don’ t know if all boilers go to highest capacity and then modulate back, For those that do, I read a study that might be enlightening. It has real fuel us data and compared the same system with the highest firing locked out and with that available. The highest fire locked out mode resulted in lower fuel use and heated the home just fine.
Could you provide a link to the study? Sounds like it's worth reading.

Nice thing about the mod-cons are that you can limit the fire rate for space heating vs. DHW heating independently.
My indirect DHW tank can adsorb the HTP-80's full fire rate of 80k BTU,s where my baseboard system can't- so I can limit it's fire rate to 50k BTU's or so based on my actual radiation capacity.
 

NY_Rob

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If said manufacturers provided a set back recovery mode vs. making you use the flat out 100% output, anyone could use set backs efficiently. I believe that some boilers can approach that if you tweak the settings, but I’ve not seen any discussion of links to better thermostats that would allow them to distinguish a set back from a deficit.
The Lochinvar Knight Boilers have a true 7-day programmable night setback feature for both space heating and for DHW tank, but- they're 2x the price of the HTP units- and they require P/S piping with the requirement of an additional system circulator (plus CH circulator, plus DHW tank circulator).

If you use a mild night setback, you can pretty much accomplish the same thing using the programmable Boost feature on the HTP boilers.

The Boost feature has three parts:
- Boost Function:
When Outdoor Temperature Mode is used, Boost Function increases the CH set point temperature by the Boost Degree temperature at time intervals (Boost Interval). Boost continues until the boiler reaches the maximum supply temperature set point based on the outdoor reset curve. The boiler will return to normal operation after the thermostat is satisfied.
Range: 0 - 120 min

-Boost Degree:
Sets the temperature added to the boiler target set point based on the Outdoor
Temperature Mode reset curve. Range: 5 - 15F Default: 10F

-Boost Interval:
Sets the interval time when the boiler will increase the temperature by the Boost Degree. Ex: Initial Boost: 10F. After 20 MIN Interval: Boost will increase CH set point temperature another 10F. After another 20 MIN Interval: Boost will increase CH set point temperature another 10F. This will continue until the boiler reaches the maximum supply temperature set point based on the outdoor reset curve, or until the thermostat is satisfied.
Range: 0 - 120 MIN Default: 20 MIN
 
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_Jerry_

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Hi Rob,

Sorry for hijacking your old thread. Very informative post! Thank you and many others who contributed.

I am in 11791, not too far from you geographically. I am looking to replace my existing 1980s gas boiler possibly with the HTP UFT-80 unit. I will make separate post with specific technical questions on another date after some time to digest everything. Quick questions on installation if you do not mind sharing, or if this board allows.

Where did you end up purchasing the HTP unit from?
Who did you end up hiring to install this specific modcon unit? You mentioned earlier that the closest contractor with experience was from Buffalo. I assumed you found someone more local since?

Thanks,
Jerry
 
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