New modcon boiler decision

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Old 11-14-08, 05:56 AM
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New modcon boiler decision

I,m looking for some advise on a new modcon boiler these are my choises: Burnum Alpine 150,Utica UB95M-200, Munckin 140M and maybe TT prestige 175.
How would you rate these as ease of installation, reliability and value. My father inlaw who is a retired boiler enginear is hooking it up. Let me know if you need more info.
Thanks.
 
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Old 11-14-08, 08:27 AM
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What's the actual heat loss calculation on the house?
 
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Old 11-14-08, 04:57 PM
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Originally Posted by Who View Post
What's the actual heat loss calculation on the house?
around 115'000-120'000 and I have a 45 gal indirect and hydro air heat.

I'm also considering a Buderus gb142/45 that I looked at today and seems like pretty good deal.
 
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Old 11-15-08, 08:54 AM
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If that's your actual calculated heatloss, then personally, I'd go with a Prestige 110. What temperature will your hydro heat exchanger require? Will it be able to return condensing temperatures? (under 135F)
 
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Old 11-15-08, 04:17 PM
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Ahh yes, I just found out about that 135 temp range for condensing boilers to run there best. I really don't know what temp hydro should be set for, right know my existing boiler is at about 170. I'm in the process of finding more software to do a more accurate heat loss test.
 
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Old 11-15-08, 05:10 PM
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Okay, my air handler says max btu at 140* water temp =51.10
and the existing boiler is set at about 150-160 right now. So does that sound about right for good efficiency/condensing with a mod/con?
 
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Old 11-15-08, 06:51 PM
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Hydro-air

With hydro-air, you certainly don't want to run the water temperature any lower than 140. If you do, you will likely find the air coming out of the registers to be uncomfortably cool. Does "heat pump" mean anything to you?
 
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Old 11-15-08, 07:23 PM
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Heat pump, no not really.

Do you want the return temp to be below 135*?

Yes I know, I'm an idiot... but what do you expect form a carpenter trying to figure this stuff out.
 
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Old 11-15-08, 09:22 PM
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Let me explain that you are far from an idiot. I have been installing boilers all my life and am still learning everyday, especially about those mod con boilers and such.
The idiot is the one who thinks he knows it all and asks no questions.

I do not get as far into the numbers game as few of the guys on this site, but I have installed 3 Munchkin boilers so far and love them, as well do the customers..
Pay close attention to the installation instructions in these boilers and be prepared to spend quite a lot more for initial investment compared to a standard boiler.
 
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Old 11-15-08, 10:10 PM
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Johnny, what Grady meant was that the SUPPLY water to the hydro-air coil doesn't wanna be much less than 140. The air coming out the registers will feel uncomfortably cool when it's drafting around the room.

So, you will need to set some minimum temp for those coils.

The RETURN temps from the coils could still be pretty low ... probably low enough ... if you figure you will have at least a 20* temp diff across the coil, that means 120* water going back to boiler.
 
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Old 11-16-08, 05:06 AM
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Most of the guys are running a foot temperature of 130f - 140f on the mod/cons for duct coils. I know more of the manufacturers are raising the foot temp from the factory set at 130f. If you want to turn it down you you may be required to use a password to get into the parameters for lowering the temp.
At 9% CO2 this is not a condensing range.
We cannot determine a 20f delta tee in a system unless it is designed as such. This means having the proper coil size for 140f water and of course the proper flow rate for a 20f delta-T. How many times does this happen in real life. We also assume a 20f delta-T in radiation which only happens at design water temperature. If the system was not designed, just installed BB on all exterior walls, what is that water temperature supposed to be? Who knows. For BB it is normally stated at 180f. That is at the designed flow rate. A system with a 20f delta-T at 180f water may only have a 10f delta-T at 140f. (Just guessing at this Delta-T). Try it sometime. Get a cold zone, cold boiler, and watch the delta-T change as the supply water temperature changes.
If you want a 20f delta-T in a duct coil you need to know what the spec's are from the manufacturer of the coil to match your heat loss. They can supply you with the flow rate, cfm and entering water temperature.
That means sizing the pump properly, sizing the pipe properly not just looking at the tapping on the coil, installing a circuit-setter for proper flow, and properly adjusting the fan. Unfortunately only has 3 or four speeds to choose from or variable fan. This is a better application.
 
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Old 11-16-08, 08:07 AM
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Johnny, all this stuff about the water temp aside for a minute...

Your stated heat loss seems high to me.

Unless, it's a large building, or a VERY lossy smaller one ...

How many sq ft is the home ?
How would you rate the windows/doors ?
A lot of glass ?
How much insulation ?

You could well be installing an oversize boiler that you will pay for for the next 20 years ...
(although, since you have an indirect water heater, the boiler may need to be sized for that...)

rbeck, where did that 9% CO2 figure come from ? I'm confused about that !
 
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Old 11-16-08, 08:26 AM
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Originally Posted by NJ Trooper View Post
You could well be installing an oversize boiler that you will pay for for the next 20 years ...
(although, since you have an indirect water heater, the boiler may need to be sized for that...)
If a hot water priority control is used, the boiler size will not change unless the water heater manufacturer is spec'ing a minimum BTUh factor, higher than your heating BTUh factor. I think I wrote that correctly.
 
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Old 11-16-08, 08:56 AM
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I built the house 8 yrs ago, started out as a 1200 sqf ranch. I totally gutted it and turned it into a 3200 sqf colonial which includes a 700 sqf familyroom addition with 12' ceiling and 3 car garage under. Every thing is insulated with r13 walls r19 floors over basement and garage ceiling and r30 ceilings. 30 windows that are double pane insulated and low e coating as well. All exterior wall are tyvex house wrapped also. Indirect Triangle phase III water heater and anti- freeze in the system. The current oil burning boiler is the origanal 110'000 btu about 40 yrs old.

I really appreciate all the help and info you guys are giving me,Thank you.
 
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Old 11-16-08, 09:44 AM
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I just did some IR temp readings.

At the boiler readings:
supply out of the boiler- 155*-165*
return to the boiler- 122*-130*

At the air handler readings:
Supply at AH coil- 150*
return at AH coil- 130*

air temp out of the closest register from AH- 135*
air temp out of the farthest register from AH- 110*

Don't really know if this helps with anything?
 
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Old 11-16-08, 04:21 PM
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Running about a 35 delta T which sounds like you are lacking some flow weather it be air, water or both. What size pipe and how far from the boiler is this coil?
 
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Old 11-16-08, 05:06 PM
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IR thermometers aren't always the most accurate things in the world... if you measure any copper pipe, paint the spot flat black. You could try black electrical tape too ... the problem is with the 'emmisivity' of the pipe ... cast iron or steel pipe will be pretty close... but copper gonna give ya error ...

I would guesstimate your actual heat loss less than 100K ...

Mark, that's what I meant ... that the boiler might need to be sized to get the recovery time on the indirect water heater ... and it will probably be larger than the heat loss of the home.
 
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Old 11-16-08, 05:18 PM
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Johnny, are you basing the heatloss on the previous boiler? If your previous boiler is a 110 MBH capped at 150 and holding down the fort, then you may be oversized. Does it run more than half the day when it is really cold out? Reality is even better than Manual J calcs at times.

They do make special air handlers with better transfer of the coils that allow lower temps. Have you given any thought to just dumping the air handler and gets some panel rads for those rooms perhaps?
 
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Old 11-16-08, 06:08 PM
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Okay, I've done what I believe to be more accurate heat loss calcs and now I'm coming up with more like 80'000- 90'000 range. I'm pretty much sold on a TT prestige solo 110, what do you think?

The air handlers are about 50'(basement) 25' (attic) away from the boiler and feed with 3/4" copper pipe.
 

Last edited by JohnnyO556; 11-16-08 at 08:21 PM.
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Old 11-16-08, 07:14 PM
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I think you should buy a Solo 60, drop ship it here and I'll send you my almost 2 year old Solo 110 (was the smallest sized unit at that time). Sound good? Beer 4U2
 
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Old 11-17-08, 03:53 PM
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Originally Posted by Who View Post
I think you should buy a Solo 60, drop ship it here and I'll send you my almost 2 year old Solo 110 (was the smallest sized unit at that time). Sound good? Beer 4U2
Sounds good... You just sit and wait for it, be there any day now.

I just got a price from the local supplier $2600 for the solo 110, not bad right?
 
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Old 11-18-08, 11:15 PM
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Pretty good... there is a suggested dealer price list on the T-T web site if you know where to look. Sounds $300 lower than I'd expect.
 
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Old 11-23-08, 09:14 PM
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I got the Solo 110 and I have a couple more ?'s.

First, my current system has the circs on the return side of the zones and the Solo manual shows them on the supply side, I plan on doing exactly how the manual shows but just what to know why the difference.

Second, why do you need flow checks on both supply and return sides of each zone.

Third, what is the best way to put the anti-freeze in the system. I was planning on pumping it through a T with a boiler drain valve in the supply line after the boiler isolation valve and before the air scoop. What do you think?

You guys have been such great help that this is now the place I come for advice and answers, Thank you so much.
 
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Old 11-24-08, 04:14 AM
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The reason for the location change of the circ's is air elimination. So what changed you may ask? The circulators. We had bigger 3 piece circulators like the Taco 110's and B&G 100's which moved many gallons of water so the water velocity helped to rid the systems of the air. In the late 50's we got introduced to the newer wet rotor circulators which can move as much water in the larger size's but now have a choice to match the system better at lower gpm flow and less electric use. The circulator will always have more pressure on the discharge side of the circ than the inlet. The circ has the ability to add pressure or deduct pressure from the system. On the supply side pumping away from the expansion tank connection (point of no pressure change) you have two things going for you. 1. As you heat water you drive the oxygen out of the water, the hot water passes through the air separator and gets rid of it. 2. The expansion tank holds the pressure on the inlet side of the pump to 12 psi and therefore the pressure on the discharge side of the pump goes up. The addition of pressure to the system helps break up the air into smaller bubbles so they can move down a vertical pipe easier to reach the boiler so they can be heated and start leaving the water and off to the air separate.
In a summary, To rid the old systems with 3 piece circ's we used moving water to rid the system of air and today we use added pressure.
Very few system require flow checks on both sides of the system. The have been cases where the flow checks were required on the return side.
Are you sure you need antifreeze? Adding antifreeze will change the heat transfer and water flow. What state do you live in?
 
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Old 11-24-08, 07:03 AM
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I live it CT and one of the air handlers is in the attic so I'm pretty sure I need anti-freeze.

The Solo manual piping diagram shows flow checks on each side of each zone?
 
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Old 11-24-08, 07:57 PM
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Originally Posted by JohnnyO556 View Post
The Solo manual piping diagram shows flow checks on each side of each zone?
Yes - on page 21 of the Solo 110 manual Fig. 9 shows flow checks on both sides of the zone in the "Zoning with Zone circulators" schematic.

I am planning on this type of installation but was under the assumption that Grundfos circ pumps have built in check valves - is this correct?

If a circ is on the supply side, then is a flow check necessary to keep warm water out of the return side of a zone? Is there a possibility of a gravity induced heat exchange between active and idle zones?
 
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