Hot water PIPING size ?

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  #1  
Old 10-26-08, 09:43 AM
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Unhappy Hot water PIPING size ?

I am installing a new boiler system (LAARS mini therm 160,000btu) - http://www.laars.com/products/reside...?uniqueID=JVST - to replace the old sears monster 155,000btu.

The old system heated a total of 15 cast iron radiators within 2 floors.

Q # 1 -The orig supply & return piping is 2" steel pipes and heading up to the radiators appears to be mostly 3/4. The new boiler inlet & outlet pipe size is 1-1/4, is it OK for me to reduce this to 3/4" & run my pump, zone valve etc up to the 2" loop? Photos are below so you can see my dry run so far:

Q # 2 - I have this huge expansion tank which is 1'x5' (I drained it, but didnt notice any place to add air, is this normal), now should I just connect to it again, or install an air separator & expansion tank?

Q # 3 - The original pump was a B&G 100 series & I do not want to use this due to the oiling & mess, I installed a taco 007, do you think this will suffice, if not how can I determine which pump will be best for my system & which do you reccommend.

Q # 4- I eliminated the control flow valve because I am installing a 3/4" zone valve, I read that you can eliminate the control valve if you install a zone valve?

Now I do want to mention this: what prompted me to go with the 3/4 pipe is), the circulator pump (even the large old B&G), the zone valve orifices (and almost all the piping to the radiators (as well as the radiator passages) are all no larger that 3/4, so if they all cause this reduced pressure/flow etc, then why 3/4" can't just do the job successfully here as well?

What is the worst that could happen?

I would really appreciate some expert advice.

Thanks
Tom

Link to Tom's Photobucket album
 

Last edited by NJT; 10-26-08 at 05:54 PM. Reason: removed broken links, added link to album
  #2  
Old 10-26-08, 02:56 PM
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None of your pictures opened.
First off I hope you did a heat loss. This a an expensive to go buy a boiler and not know what size is needed. Most old boilers are 100-200% oversized. This causes higher fuel bills, more failure of parts due to short cycling and more boiler issues.
The piping attached to the boiler must be 1-1/4" with a bypass and primary.secondary will be best. It cannot be reduced to 3/4". it is very important to have the proper flow or you will ruin the boiler with no warranty.
You should install an air seperator with a new diaphram tank.
Is the 007 large enough? don't know you need to what the resistance to flow is.
You can use a zone valve instead of flow valve but you need to have the proper flow or your boiler will make alot of noise and banging.
Sounds like you went into this project trying to figure it out as you go rather than getting the facts first. Now it is getting crunch time as the weather is changing.
 
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Old 10-26-08, 04:55 PM
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rbeck,

I dont know why the pics didn't open... try these:

http://i462.photobucket.com/albums/q...x/IMG_5244.jpg
http://i462.photobucket.com/albums/q...x/IMG_5245.jpg
http://i462.photobucket.com/albums/q.../IMG_5256w.jpg

Thanks for you response and yes I did just dive into it , but not after some serious speaking to many manufacturers tech persons and I do want to point out several things (so you don't think I just went out & bought just any boiler system Beer 4U2 ):

1- When the outside temp drops below 20 degrees this house will not reach more than 65 degrees, 10 degrees, it's like 60 & 0 degrees, 50 , so I don't think I'm over sizing and another very important thing I want to mention is I may eventually be heating the attic & basement. Now another VIP thing I want to mention is this model boiler is it has a "2 stage feature", which will only produce 1/2 of it's BTU capacity if less is needed (this is a very unique feature), so I'm quite confident that I made a wise decision as far as sizing.

2- Now I was originally going to go 1-1/4 up to the 2" pipes, (which branch out to the radiators with 3/4), but when I looked at the pump & zone valve carefully, I noticed how they both have reduced paths which are closer to 3/4, so I figured why would I need to run 1-1/4 up to them and after them.

Let me put it another way, the circulator pump (even the large old B&G), the zone valve orifices (and almost all the piping to the radiators (as well as the radiator passages) are all no larger that 3/4, so if they all cause this reduced pressure/flow throughout the system, then why would 3/4" be a problem at this point?

Can anyone explain ?

And as far as leaving the old tank, read what NJ Trooper wrote here, he suggest to leave the old one on, is he incorrect?
http://forum.doityourself.com/showth...on+tank+sizing

Thanks
 
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Old 10-26-08, 05:49 PM
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he suggest to leave the old one on, is he incorrect?
No, that's not what I said at all.

My point was that it isn't as easy as just replacing the old tank with the new bladder tank. You need to do some repiping and add some extra components. You need an air separator and an automatic air vent.
 
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Old 10-26-08, 07:35 PM
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Originally Posted by NJ Trooper View Post
No, that's not what I said at all.

My point was that it isn't as easy as just replacing the old tank with the new bladder tank. You need to do some repiping and add some extra components. You need an air separator and an automatic air vent.
Sorry if I misunderstood you, so are you saying that one should replace their large old tank and add an air separator and an automatic air vent, why do this if the old one was doing the job?
 
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Old 10-26-08, 08:24 PM
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Because the modern bladder tanks do a much better job keeping the system free of air, and they are easier to maintain. That old tank would probably need draining every other year, if not every year, if not 2-3 times a year... all you really need to do to maintain a bladder tank is check the air pressure...

How can I say this... there is a lot that needs to be learned and understood before one can successfully install a boiler system.

Let's start with your pictures...

Didn't the boiler come with a 'vent damper' ? I don't see one in your pictures. The boiler won't even fire if you don't install that and plug in the wiring harness. What I do see is a piece of dryer vent connected to the flue pipe ... what is that stuff?

Your system is a LARGE volume system. You can't just connect the in and out of that boiler to the pipes without taking that into consideration. The water that returns from those radiators is going to be cold/cool for a LONG time, and this is going to play he11 with that boiler. In fact, the flue gases condensing inside it are gonna ruin it ... not to mention that if you don't pipe it according to the manual, the warranty is going to be void. In fact, most manufacturer warranties are void from day one if the appliance isn't installed by a qualified, licensed heating contractor.

Did you read and understand the installation manual ?

In particular, Section 5, starting on page 12. Understand that your system DOES qualify as a LOW TEMPERATURE system due to the simple fact that it is going to take a LONG TIME to heat that large volume of water.

These Laars boilers are VERY sensitive to having the proper flow through the unit. They MUST be piped properly, and according to the manufacturers recommendations. Did you notice how many times the manual said "Warranty is void if ..." ?

Don't think for a minute that if your house did not heat well with the old boiler, that this new boiler will be a 'magic bullet'. Deficiencies in the original installation are probably to blame... and the first step in getting energy costs under control should be INSULATION in the home, and correcting any INFILTRATION problems.

I believe that you are misunderstanding the 'high fire / low fire' feature of this boiler. Fact is, that most of the time it will be operating at high fire. It all depends on the temperature of the water in the boiler, and believe me, it will rarely, if ever, go to low fire with your system... UNLESS it's properly piped.

Can anyone explain ?
It's all about FLOW and VELOCITY. You don't want water SCREAMING through the heating pipes. You want the water to move at something like 2-4 Feet Per Second (FPS). In a 3/4" pipe, that means about 4 Gallons Per Minute (GPM). You can move approximately 10,000 BTU for every 1 GPM of flow. Therefore, in a 3/4" pipe, you can move 40,000 BTU at an acceptable FLOW rate. But, that boiler is around 140,000 BTU! In order to move FOURTEEN GPM at 2-4 FPS, you would need a pipe that is ONE and ONE QUARTER inches in diameter. So, now you see why those pipes on the boiler are that size ?

Pumps are designed the way they are designed because that's the way they work... yes, it appears that it's 'choked' down, but they are DESIGNED to work that way. Pumps add ENERGY (or HEAD) to the water, and they can't add that energy with huge, cavernous insides. It would be like trying to stir a garbage can full of water with a toothpick.

If there are 3/4" pipes going to the individual radiators, it's because only a PORTION of the flow is going to that radiator.

I think I've given you enough to think about for now... and honestly, I'm not trying to be cruel, just my opinion, but I believe that you are in over your head. If you had started this project in May, you might have enough time to learn what you need to learn, and apply it to the installation at hand. But now... I dunno ...
 
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Old 10-26-08, 10:46 PM
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NJ Trooper,

Thanks for ripping me apart & making me feel like a total idiot (just joking)... at this point maybe it would be best for me to build a igloo & cry?

No seriously, I need some encouragement here, I can just call a plumber, but prefer this challenge (because I am disturbed), lol... honestly now, do you believe that even if I run 1-1/4 to the 2" pipes, this unit will still not work properly?

And I still don't understand why these pumps & zone valves have small flow openings... doesn't this still pose the same flow problem you are suggesting even if I install the 1-1/4 pipes?

Yes the boiler did come with the damper, but I'm just focusing on the piping 1st & the dryer vent is temporary as well.

As for the tank, I never had any air problems with it, but if you strongly beleive I should replace it with a new bladder tank, I will (but do I have to get the same large sized unit like the existing one?)

BTW thanks, I appreciate your knowledge & looking at the manual etc, I'm sure this will be a lesson to many others?
 
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Old 10-27-08, 06:20 AM
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As far as the temp issues it may not be a boiler problem. It can be flow or amount od radiation. What was your heat loss? That is how you size a boiler, not to the amount of radiation, not off the old boiler, not on sq ft or cubic foot but by a heat loss. I always say the problems in a heating system start with the sizing of the boiler.
Next is flow. This boiler should have 16 gpm flow. Not in 3/4" pipe it wont. You must realize you need flow in all the radiators not just one. If you fire this boiler with 3/4" pipe you will destroy the boiler.
There is no problem in keeping the old tank but most change it out. The newer tanks are a tank which must be maintained. The old style tank is a maintenence free tank if properly installed. Piped to an air seperator, not less than 3/4" pipe, all piping slope up hill, no valves in the horizontal piping, no automatic air vents to name a few. If properly installed no need to drain.
 
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Old 10-27-08, 07:44 AM
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Tomzy,

Tough as it may be to take, Trooper and rbeck have made some very important points. Let me add a bit to that (call it piling on if you want...). First the bad, then the good.

In the category of "water under the bridge," we have:

1) you didn't do a heat loss before sizing the boiler. Chances are this thing is 2-3 times bigger than you need. Even if it has a half-input firing rate, a boiler sized to the heat loss will save you money over the long term. A boiler is theoretically a 20+ year appliance decision. It really does help to size it right

2) you didn't plan out this installation beforehand. You really can't wing this stuff as you go. Or at least you shouldn't.

3) you apparently didn't read or understand the installation manual. The manual is quite straightforward, including the flow rate requirements and the primary/secondary or bypass requirements.

In the category of "ok, so how can this be fixed up so it works safely and efficiently," we have

1) you need to read, understand, and follow the installation instructions. They have a decent writeup and good diagrams that cover a variety of installation scenarios, including yours. Among other things, the boiler should be piped primary/secondary and have a dedicated circulator to provide adequate flow. There's a reason they require 1.25" piping -- because you cannot shove 16 gpm through 3/4" piping. Try blowing 30 cfm through a cocktail straw sometime.

2) if you follow the directions, you'll see that you end up with a boiler loop that has an adequate flow rate so the boiler can function normally and efficiently. You will also have system (space heating) loops with zones controlled by circulators or zone valves, and those will be sized to provide adequate flow through the space heating loops.

3) my suggestion is to get a cup of coffee, sit down and read the manual. Figure out which piping scheme you want to use, and follow it to the letter. The diagrams are sufficiently complete that this should not be too difficult.

4) you will end up with a boiler loop that is composed of 1.25" piping, and uses either primary/secondary or a bypass approach. See pages 12-15 in the manual. The boiler loop will connect to a manifold that might be 2" diameter, and have the takeoffs for your zones. The return manifold will look similar.

Good luck. Believe it or not, people are here to help, not tear you down. There have been a number of excellent recent DIY installs that this forum helped to inform (e.g., the one by GEEVEE is really sweet).
 
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Old 10-27-08, 08:05 AM
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Thanks

xiphias,

Thanks for the encouragement, I certainly needed it at this time.

Tomzy
 
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Old 10-27-08, 09:29 AM
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Tomzy,

All the posters bring up the very important point that you cannot guess what components (like piping size, circulator pump, etc) you need in a heating system.

It is a science and I would suggest the following:

1) Go to http://www.taco-hvac.com

And download document TD10 "Taco Radiant Made Easy Application Guide". It is one of the most detailed and best documents I have seen for sizing pipes and circulator pumps in a heating system.

I went through the calculations and found my circulator pump from 1955 was supersized and a small pump (likes a B & G series 100) would have done the job. It also proves the point many posters made about incorrectly assuming the original installation was done properly.

2) Go to http://www.bellgossett.com

Download the documentation for your B&G series 100 pump.
You will need the Head vs gpm curves for the final calculations in the TD10 document.
 

Last edited by reno1962; 10-27-08 at 10:19 AM.
  #12  
Old 10-27-08, 04:44 PM
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Rooting through the B&G site now, because there are a bunch of good articles there:

"Zoning Made Easy" textbook

B&G Tutorials

By the way, I believe you have gate valves installed... FULL PORT BALL valves are a much better choice...
 
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Old 10-27-08, 06:21 PM
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Trooper,

Thanks, actually I ran into those, but I just haven't found the time to study them!

Why do you suggest the ball valves?

Thanks
 
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Old 10-27-08, 08:44 PM
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Ball valves shut off all the way. Gate valves drip, drip, drip ... gate valves can get STUCK, open or closed, and you can turn that handle and twist the lift rod right outta the gate ... (they 5uck in my opinion).
 
 

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