Hydronic replace old boiler-gravity conv-2 pipe- Near Boiler piping and bypass?

hot_rod

TommyA said:

Greetings. First post so take it with a grain of salt . And I'm probably too late for @OldawgBryant , but I am currently (as I type!) going through the same process using the Caleffi 280 and wanted to share some real life experience. Similar situation, old gravity system converted to forced circulation many years ago. Time for a new boiler. Not a heating guru...

Regarding the Caleffi 280, great valve but two things to note/be aware of:

1) There is no way to manually open the mixing valve. Meaning, when the system is cold, water is trapped on the cold side of the valve. Add a drain! Luckily for me I just happened to locate my DirtMag right there and was able to use it to drain the return side. Otherwise I would have had to drain many many gallons through the unions!

2) And maybe more importantly, I too was trying to get by with a single circulator (no primary/secondary). But what I noticed was that until the 280 mixing valve is fully open (which for me happens at 158 degrees) you're only getting a trickle of water out to/from the system. Nothing close to what your circulator is producing. So for the hours+ it takes to heat 100 gallons of water, I'm basically back to a gravity system. Which would be okay if it hadn't been modified over the years to include some wonky branches which got no flow at all (cold radiators).
So your mileage may vary, but this week (after my parts arrive from SupplyHouse.com) I'll be reworking the upper section of my piping to create a secondary loop with it's own circulator so I can force all that water around the conveyor belt! Fortunately I can do it in such a way to leave the near boiler piping alone.

Thanks for the good data on your system..I’m thinking maybe the bottom port here you change the cartridge could have a small drain cock?

As far as operation, I think it is proportional, in 80% is bypassing back to the boiler, 20% goes to the system. 40% to the bypass should have 60% going to the system.

So is is attempting to give the system just as much as the boiler can keep up with.

Let me talk to Italy about these observations.

Which cartridge do you have? If it takes 158 to close the bypass 100%, it sounds like the 140 cartridge? I could send you a 130 to try, which should speed up the action, so at 148 you should see 100% to the system. PM me your address if you want a lower temperature.

Also I get one to install at my shop, add some flow meters and clear piping to see how it works across the temperature ranges.

EricPeterson

@tommya - no time to elaborate right now. Briefly - the bypass I added was just in case the valve did not work properly; I'm a wary person. With the bypass I would have simply had the water flow going the way it was before. I can explain more later.

Eric

TommyA

@hot_rod Just sent you my address. Yes, using the 140 cartridge so I'll take you up on that offer! Thank you!
And I agree with you that it's proportional in how it works. I guess in my case, while the valve is doing its proportional thing, I'm not getting enough water circulated in the system to overcome some of the juggernauts. I just failed to consider this and hoped to make others aware. The thermostat is satisfied before the valve fully opens (which is a good thing I guess). But not having the desired flow is leaving me with a couple cold radiators!

hot_rod

Yes with a single pump system, you need to assure the pump can supply adequate flow to the system, under any condition. The 280 doesn't add much flow resistance, it is a high Cv valve.

If you have a string of radiators in series, at the low flow condition you may be seeing too much temperature droop. But at the same time it is protecting the boiler.

I'll send both a 130 and a 115°, like I did Eric, see if either helps a bit. The 115 with the 16° differential should still get you 131° when bypass is completely closed.

OldawgBryant

@TommyA @EricPeterson @hot_rod this is good to know, as I'm just applying the tape & dope and have started assembly. But I did the manual bypass also (like Eric). What's your Edr on the house? Sq feet? What size is the boiler? I don't have 100 gals, more like 55-60 with the old boiler and the old boiler had about 8 or so in it (I think the new one has only 3 gal or so) I have the 130 Cartridge, but may go for the 115 depending on how things work. I do have A Webstone ball valve drain on the return before the mixing valve, to drain the return, if needed and also the dirt-mag like you have. How many minutes before yours got to temperature?

OldawgBryant

@TommyA the piping looks pretty good, is that 1"? What pipe dope did you use on those joints?

EricPeterson

TommyA said:

Greetings. First post so take it with a grain of salt . And I'm probably too late for @OldawgBryant , but I am currently (as I type!) going through the same process using the Caleffi 280 and wanted to share some real life experience. Similar situation, old gravity system converted to forced circulation many years ago. Time for a new boiler. Not a heating guru...

Regarding the Caleffi 280, great valve but two things to note/be aware of:

1) There is no way to manually open the mixing valve. Meaning, when the system is cold, water is trapped on the cold side of the valve. Add a drain! Luckily for me I just happened to locate my DirtMag right there and was able to use it to drain the return side. Otherwise I would have had to drain many many gallons through the unions!

2) And maybe more importantly, I too was trying to get by with a single circulator (no primary/secondary). But what I noticed was that until the 280 mixing valve is fully open (which for me happens at 158 degrees) you're only getting a trickle of water out to/from the system. Nothing close to what your circulator is producing. So for the hours+ it takes to heat 100 gallons of water, I'm basically back to a gravity system. Which would be okay if it hadn't been modified over the years to include some wonky branches which got no flow at all (cold radiators).
So your mileage may vary, but this week (after my parts arrive from SupplyHouse.com) I'll be reworking the upper section of my piping to create a secondary loop with it's own circulator so I can force all that water around the conveyor belt! Fortunately I can do it in such a way to leave the near boiler piping alone.

@TommyA - I don't understand how you are only getting a trickle of water to/from the system when the valve is 100% open. You should be getting full flow through the system. Since you can't really see the valve, I presume you are assuming it's open based on a temperature reading. Could the thermostatic element be bad, or is there something else in the path that is blocking water flow?

As I said, my install works great. The only differences I see are:

1. you are pumping away from the valve and towards the return whereas I am pumping towards the valve from the supply.
   
2. You have an expansion tank and air remover, whereas I have a compression tank and an air separator.
   
3. You have a DirtMag and I have nothing like that.
   

I have temperature gauges at the boiler return, the boiler supply, and the system supply. When the boiler fires up I can observe the temperature at the return rise to 140F in about two minutes. Then the valve starts to open and I can see the supply temperature to the system start rising. One other difference might be that my setpoint is 180F.

I have three zones:

• Family room with 9" baseboard,
  
• Living area with three free-standing radiators and 9" baseboard
  
• Bedrooms and bathrooms with six free-standing radiators and 6" baseboard.
  

I have not experienced issues with any of these zones heating normally.
The only issue (so far - fingers crossed) is a slight whine from the circulator when the valve is closed. It goes away once the valve starts to open.

Eric Peterson

OldawgBryant

@EricPeterson That's kind of how I thought it was supposed to work. And you have your "bypass" of the Bypass closed, right? This is a good conversation, as I see how I have not designed my manual bypass of the mixing valve correctly and will fix it to be like what you did.

EricPeterson

@OldawgBryant and @TommyA - it's hard to convey the design details in words. But here is a summary of what I've done to address the return temperature, followed by a picture:

• 2010 - initial boiler install. When piping the new boiler, I added a system bypass by connecting the supply to the return, modulated with a ball valve. The idea was to mix heated water with water from the system. I left this valve at about 45 degrees (half-open). This was a "short-term" fix, haha until I got around to installing a thermostatic valve.
  
• 2023 - added the Caleffi valve. In so doing, I teed the system return water so it went to both to the boiler return, and to the Caleffi. But I also added a valve between the system and the boiler so that all water went to the Caleffi, and this valve is normally closed, as is the original "system bypass" valve.
  

Below is the diagram I made, and the following applies:

• Normal operation - water moving through the Caleffi valve:
  • Closed: V1 and V2 (diverts all water through the Caleffi valve)
    
  • Open: V3, V4, V5
    
• Maintenance - Caleffi valve taken out of the loop:
  • Closed: V3,V4,V5
    
  • Open: V1 (provides path from system return back to boiler)
    
  • Partially open: V2 (bypasses some heated water back to the return)
    

Hope this helps!
Eric

TommyA

@hot_rod Thanks! Looking forward to trying those out, especially the 115. Quick question... can I simply remove the cartridge and have it run 100% open (as a test) or will that leave both hot and cold ports wide open? I think I know the answer .

@EricPeterson Sorry for any confusion. What I meant was that I'm getting a trickle of flow UNTIL the valve is 100% open. That was really the point I was trying to make. I designed using delta-T and GPM and so on, but it all goes up in smoke while that valve is throttling. I'm getting so little flow (and big ol' delta-T's as @hot_rod pointed out) that things are heating unevenly or, for some radiators, not at all. I was just hoping to make others aware of my mistakes so they can learn by them. I really need to go primary/secondary piping.

@OldawgBryant Yes, it's 100 gallons (I measured using 5 gallon buckets when I drained the old system. Inquiring minds wanted to know ). I calculated 40,000 BTU load for my smallish house, so I went with the Weil-McLain CGa-3 (46K net). Should get the job done, but maybe all that water is killing me . Yes, 1" near boiler piping, but where I tied the old 2.5 inch supply lines together I used 1.25" (same for the returns). Blue Monster PTFE tape combined with Hercules Blue-Bloc dope. The boiler supply temp rises to ~152-156 in a few minutes but then hangs there for well over an hour while the mixing is taking place. The boiler return temp is ~142-146 while all this is going on. I'm running 5GPM through the boiler (or at least that what my Taco 0018e is telling me). This would translate to .5 GPM (or .25 for each branch) while the valve is at 10% .

So, because I cut it so close with the boiler sizing, I'm adding the secondary loop and another circulator so I can push the water faster through the system to keep the temp drop lower and overcome some thermal traps introduced by system mods over the years. Wish my wife would have let me buy a mod/con so I could run this below condensing temps .

hot_rod

I've know installers that have undersized 3 way thermostatic valves on radiant system that have removed the guts and let them run.
I ordered a 280 today to try some of these suggestions.

When you remove that bottom cap I think it is spring loaded. just so you don't lose parts or the order to re-assemble it.

EricPeterson

TommyA said:

@hot_rod wrote

As far as operation, I think it is proportional, in 80% is bypassing back to the boiler, 20% goes to the system. 40% to the bypass should have 60% going to the system.
So is is attempting to give the system just as much as the boiler can keep up with.
Let me talk to Italy about these observations.
Also I get one to install at my shop, add some flow meters and clear piping to see how it works across the temperature ranges.

I am interested to see what you find out about how the valve operates.
My only experience with such thermostatic devices is from working on cars 40 years ago.
If the valve is closed at 140F, and fully open at 158F, based on the temperature of the mixed water, it is partially open between those two points.
So is it linear - e.g. 50% open at 149F?
Or does it follow some other curve?

Eric Peterson

hot_rod

Here is what drives wax motor type thermostatic valves. 3 way valves, TRVs, thermal balance valves, etc.

I don't think there is much intelligence here

It's paraffin wax and pulverized copper.

As it pushes the cartridge inside, one window opens as the other closes.

EricPeterson

What - no microprocessor? 🤣
Regardless, like a pump curve, I would expect a graph could be made of its movement over the temperature range.
It doesn’t really matter, I’m just curious.

Eric

OldawgBryant

@TommyA Yeah, I thought those stains looked familiar. I'm using the same monster tape & hercules blue block (I've always had good results, but it is messy and is not water soluable). But now I am getting my **** kicked with trying to tighten-up black pipe unions that are not holding my 20# air test...



I thank you for your mention of this valve, as I forgot to add the manual bypass (in case I want to let more return water in than the mixing valve does) like @EricPeterson did, or to bypass it Here is my set-up for that.

OldawgBryant

@Mad Dog_2 Any advice for the leaking threaded unions? I hate them and I have quite a few on my project. I already wrapped and doped the union threads... Is there a better way? Would brass better? I have a lot of vertical weight coming down on the 2 unions for the boiler. Any suggestions would be appreciated...

TommyA

Looks like cast iron fittings, nice! Believe it or not, my unions leak also! And I specifically paid more for domestic ones to avoid this. Search this forum for "leaking unions" for ideas. If I can't resolve it I'm going to swap them out with pump flanges and gaskets, as suggested by Hot Rod. Cheaper too!

neilc

OldawgBryant said:

@Mad Dog_2 Any advice for the leaking threaded unions? I hate them and I have quite a few on my project. I already wrapped and doped the union threads... Is there a better way? Would brass better? I have a lot of vertical weight coming down on the 2 unions for the boiler. Any suggestions would be appreciated...

is that leaking at the union collar?
you don't tape, nor dope, the union collar threads,
well maybe just a dab of dope as a lubricant,
but no tape and no dope job,
the seal is at the 2 casting faces,

how well does the union line up without the collar?
back off the collar and post a picture from both angles to show that alignment,

OldawgBryant

@neilc @TommyA alignment seems to be the key. These are ward fittings USA but 150 (what's the difference between 150 & 300?) I took it apart and realigned it and no more bubble bath. Now we will see if there still is 20# psi in the morning. Are flanges better? I have about 15 unions on this project and I feel like I have to be a brain surgeon to get the alignment correct.

hot_rod

A small amount of pipe dope on the mating surfaces may be needed, if the alignment is correct

OldawgBryant

@hot_rod would you go for flanges, as opposed to unions (1-1/4") are they easy to line-up?

hot_rod

Hard to beat pump flanges with a flat gasket between. Those rarely leak

OldawgBryant

@EricPeterson @TommyA @hot_rod Yes, the alignment must be pretty dead-on...adjustments made and a little dope and union no leak.

Anyone think I will have false readings with the 280 3-4" above the vent pipe? (actually it is not directly over the vent, but the isolation valve is)

hot_rod

OldawgBryant said:

@EricPeterson @TommyA @hot_rod Yes, the alignment must be pretty dead-on...adjustments made and a little dope and union no leak. Anyone think I will have false readings with the 280 3-4" above the vent pipe? (actually it is not directly over the vent, but the isolation valve is)

You could take a short piece of vent pipe and make a heat shield fastened it an inch or so above that flue pipe

mattmia2

The specific heat of the water is so much more than the air rising off the vent it won't affect the water temps.

The union is significantly bigger than the pipe it is attached to and usually requires more torque than the pipe to provide enough clamping force.

EricPeterson

OldawgBryant said:

@neilc @TommyA alignment seems to be the key. These are ward fittings USA but 150 (what's the difference between 150 & 300?) I took it apart and realigned it and no more bubble bath. Now we will see if there still is 20# psi in the morning. Are flanges better? I have about 15 unions on this project and I feel like I have to be a brain surgeon to get the alignment correct.

@OldawgBryant - the alignment for black pipe is even more critical when working in such tight spaces, as I discovered when I piped in the Caleffi valve. I had to redo one section to address the brass unions leaking, so much that I considered swapping in copper - but I was able to get them aligned.

I too did the piping in sections, pressure testing as I went along. In general I consistently threaded in all fittings to a minimum of 5/8", which is a little less than the .70 " as recommended here. I don't want leaks, but also don't want to break any fittings from over-tightening. I tried to use unions only when necessary,

As for the black pipe unions, once they are aligned, sufficient tightening usually stop any drips.
I've put pipe dope on the threads of the two sides of the union for lubrication when tightening, but not on the faces of the union.

Eric

OldawgBryant

@EricPeterson Excellent knowledge. Thanks for that link! I'm in that 5/8" area, but it depends, because I may be short a little, so I will use extra tape. I can only hand cut-thread the pipe, and I have a lot of close dimensions. I am working now to reduce the number of unions in my design also.

PeteA

@hot_rod any chance of a press 280 valve coming out soon? It would make a lot of these alignment issues with the unions and threaded pipes much easier to work on in these tight spots.

hot_rod

PeteA said:

@hot_rod any chance of a press 280 valve coming out soon? It would make a lot of these alignment issues with the unions and threaded pipes much easier to work on in these tight spots.

Good question, we may have the tailpiece on another product that would fit

PeteA

hot_rod said:

PeteA said:

@hot_rod any chance of a press 280 valve coming out soon? It would make a lot of these alignment issues with the unions and threaded pipes much easier to work on in these tight spots.

Good question, we may have the tailpiece on another product that would fit

That would be great, I'm finally ready to get mine if they to sell one to me to R&D. I'll send back photo's of the install

hot_rod

For the 1" 280 valve:

NA10497, washer R0001454, you would need 3 of these

Still looking at the 1-1/4 size.

PeteA

hot_rod said:

For the 1" 280 valve:

NA10497, washer R0001454, you would need 3 of these

Still looking at the 1-1/4 size.

excellent!! the 1" should be perfect for my purposes Thanks again for the info