Radiant Heat System Question

[Dana]

Ah, that vintage Solo had a huge jump from the -60 to the -175, with nothing in-between. The -60 is clearly not enough, therefore... The current vintages all have a -110, which would be a more appropriate size, therefore the confusion. Mind you, they probably sell a lot more -110s than -60s, and the -60 is more than enough boiler for 19 out of 20 homes out there.

Looking at the plumbing it appears to be pumped direct. On page 4 of the manual they caution that it should always be plumbed primary/secondary if there is potential for seeing water temps below 46F, which it almost surely would in the snow-melting zone.

If you valve-isolate the expansion tank then relive the pressure on the water side, you can then properly pre-charge the tank using an air-pressure gauge. You'd then open all of the isolating valves anywhere in the system, hook up a hose connected to your potable water system to ANY of the system valves with hose fittings, and fill until the system pressure is 15-18psi, assuming the highest point on the system is 30-35' above where your gauge is located. Only then would you fire the system back up. You appear to have multiple options for fill-ports and temporary pressure gauges. The bronze capped boiler drain taps with ball-valves on both sides of the bottom of the boiler appear to be hose-thread, as well as the cluster around the expansion tank.

 

[TheFerretman]

Ah, that vintage Solo had a huge jump from the -60 to the -175, with nothing in-between. The -60 is clearly not enough, therefore... The current vintages all have a -110, which would be a more appropriate size, therefore the confusion. Mind you, they probably sell a lot more -110s than -60s, and the -60 is more than enough boiler for 19 out of 20 homes out there.

Looking at the plumbing it appears to be pumped direct. On page 4 of the manual they caution that it should always be plumbed primary/secondary if there is potential for seeing water temps below 46F, which it almost surely would in the snow-melting zone.

If you valve-isolate the expansion tank then relive the pressure on the water side, you can then properly pre-charge the tank using an air-pressure gauge. You'd then open all of the isolating valves anywhere in the system, hook up a hose connected to your potable water system to ANY of the system valves with hose fittings, and fill until the system pressure is 15-18psi, assuming the highest point on the system is 30-35' above where your gauge is located. Only then would you fire the system back up. You appear to have multiple options for fill-ports and temporary pressure gauges. The bronze capped boiler drain taps with ball-valves on both sides of the bottom of the boiler appear to be hose-thread, as well as the cluster around the expansion tank.

Thank you! I am greatly appreciative of the help, but there are a couple of things you said that I don't understand (probably because you've done this more than I):

• The pressure tank is now reading ~15 psi; he was a bit low. That part was easy.
  
  
• I believe they did indeed set it up with a primary/secondary since I'm on a well. The water heating line runs from the output side via a "T" connection to loop thru the water tank, and then that comes back to the boiler.
  
  
• I don't understand "open all the isolating valves anywhere on the system" at all. There aren't any valves except on piping below the boiler proper and a couple inline to the zones and the hot water tank, and they're all open already. The manifolds all have Icma valves which are also all pretty much open (we found a couple that were inexplicably partially turned down but we fixed that).
  
  
• I do plan to get an thread-on psi gauge just to double check that gauge built into the Triangletube. It's probably correct but just in case it won't hurt.
  
  
• I have about 2, maybe 3 gallons of glycol handy. My hunch is I should go fetch another bucket before I start all of this....what do you think?

Again, thank you!

EDIT: Do I want to shut off the valves to the expansion tank when I run the fill, or leave them open? I assume I'd leave them open?


Steven in Colorado

 

[Sponsor]

 

[Jadnashua]

First off, there are only two reliable ways to precharge an expansion tank...the first is before it is even installed, and the second is if the hydronic side is entirely open to the atmosphere - i.e., NO closed valve and a place for the bladder to push the liquid with no backpressure when filling it up with the desired air pressure (and volume). Otherwise, what you'll measure is the system's water pressure, not the air pressure of the precharge. So, with that in mind, you could use an accurate air pressure gauge on the fill port of the expansion tank to check the system water pressure unless you've over pressurized the tank during normal operation, since it will always be the same as the water pressure pushing on the other side. That precharge should be approximately the boiler's water pressure. Pumping air into the expansion tank is NOT how you'd pressurize the hydronic system. If charged properly, when you closed the water valve you opened to do that, the system pressure would be zero.

Primary/secondary on a boiler is ALL within the boiler circuits and has nothing to do with supply water from your well. Essentially, the primary loop just connects the outlet of the boiler back to the inlet with its own pump to circulate the water around that one short loop. On that loop are then two T fittings where the secondary loop's supply and return fit. It is critical for their placement on the loop to be proper, or it won't work well. The separation of the takeoff and return of the secondary loop's T's must have a specific range of separation and the circulator's speed and volume must match up with the heat exchanger rate of the boiler.

Excessive micro boiling can eat away the heat exchanger...the pressure must be above the minimum, and most of them have a low-pressure cutoff that will prevent the boiler from operating if it is too low. If yours does not have one, I'd be surprised. But, it could be defective. They sometimes fail shorted out, and sometimes open.

 

[TheFerretman]

First off, there are only two reliable ways to precharge an expansion tank...the first is before it is even installed, and the second is if the hydronic side is entirely open to the atmosphere - i.e., NO closed valve and a place for the bladder to push the liquid with no backpressure when filling it up with the desired air pressure (and volume). Otherwise, what you'll measure is the system's water pressure, not the air pressure of the precharge. So, with that in mind, you could use an accurate air pressure gauge on the fill port of the expansion tank to check the system water pressure unless you've over pressurized the tank during normal operation, since it will always be the same as the water pressure pushing on the other side. That precharge should be approximately the boiler's water pressure. Pumping air into the expansion tank is NOT how you'd pressurize the hydronic system. If charged properly, when you closed the water valve you opened to do that, the system pressure would be zero.

One more time -- I am not trying to charge the hydronic system from the expansion tank. The tank itself was a bit low (thanks to Dana for suggesting I checked it), so it was charged back up while the system itself still read zero (assuming that gauge is good). While I didn't physically open a valve to air for the fill if it WAS in fact zero or close to it then it was likely the same.

Getting myself a gauge for the hydronic system today. I'm comfortable with the air gauge I used on the expansion tank.

Primary/secondary on a boiler is ALL within the boiler circuits and has nothing to do with supply water from your well. Essentially, the primary loop just connects the outlet of the boiler back to the inlet with its own pump to circulate the water around that one short loop. On that loop are then two T fittings where the secondary loop's supply and return fit. It is critical for their placement on the loop to be proper, or it won't work well. The separation of the takeoff and return of the secondary loop's T's must have a specific range of separation and the circulator's speed and volume must match up with the heat exchanger rate of the boiler.

I don't see a direct connect from the outlet to the inlet, other than the loop that runs through the hot water tank -- that could act as a loop as you describe.

My presumption here is that this was all installed properly since it's been working fine for years; I'm seeking to see if the pressure is actually low, the gauge is bad, and if it was low how to go about re-pressurizing things.

Excessive micro boiling can eat away the heat exchanger...the pressure must be above the minimum, and most of them have a low-pressure cutoff that will prevent the boiler from operating if it is too low. If yours does not have one, I'd be surprised. But, it could be defective. They sometimes fail shorted out, and sometimes open.

As noted earlier the issue began when the LWCO kept it from running.

You mention I think that the heat must be a minimum to avoid issues...I don't see anything useful in the documentation here. Do you have a suggestion I can check again?


Steven in Colorado

 

[Jadnashua]

A loop to the indirect does not, as far as I understand it, act as a primary loop. Your heating runs would come off of the primary loop, separated from each other (hot and return) by a specified distance via T-fittings.

http://www.slideshare.net/illinoisashrae/hydronic-basics-primarysecondardy-pumping

will tell you more than you want to know! Using a primary/secondary loop design means that the flow through the boiler will stay the same regardless of how many heating zones are open or closed. Otherwise, a well-designed system would need bypass valves. If you don't have a primary/secondary piping arrangement, and you designed it for all zones to be operating, when you start to shut down one or more, the head changes, which causes the flow to change, which can lead to all sorts of issues.

Every boiler is slightly different. I think the low pressure cutout on mine opens at around 5psi, but I'm not positive. Keep in mind that water pressure drops about 0.43psi per foot rise in elevation. So say your boiler is in the basement, and you have two stories, say 15' rise from the outlet of the boiler, the pressure would be 15*0.43~6.5psi lower than it is at the boiler. You need pressure everywhere to prevent problems. LIving in a vacuum can cause issues at the top. 12psi is a fairly typical running pressure, a bit more won't hurt. Mine tends to run about 16psi, which is also fine, as the boiler is designed to handle it, and the safety release is a common 30psi one. With a proper expansion tank, it never gets anywhere close (I might notice maybe a delta of 1-2psi between hot/cold).

 

[Cacher_Chick]

I am not familiar with boiler systems, but reading this thread has me curious; if the system is filled with the proper glycol concentrate, adding water to the system would be diluting the mix, and raising the freeze point of the loop, no?

 

[TheFerretman]

I am not familiar with boiler systems, but reading this thread has me curious; if the system is filled with the proper glycol concentrate, adding water to the system would be diluting the mix, and raising the freeze point of the loop, no?

You are absolutely correct, but in this case I'll be (potentially) adding more glycol. The stuff that is in there now is pink; the stuff I've found locally is blue. I don't think mixing the two will make a difference other than to turn my liquid overall to a bit more purple.


Steve in Colorado

 

[Cacher_Chick]

I would question mixing different types of antifreeze. There are a number if different types of antifreeze on the market, each having it's own chemical additives for reducing corrosion and maintaining pH. If you mix different types, you may risk the possibility of doing more harm than good.

 

[TheFerretman]

I would question mixing different types of antifreeze. There are a number if different types of antifreeze on the market, each having it's own chemical additives for reducing corrosion and maintaining pH. If you mix different types, you may risk the possibility of doing more harm than good.

I don't really think they're "different" beyond the coloring, but I take your point. I'll double check all of the ingredients and such before I do anything.


Steven in Colorado

 

[Dana]

Just because it's been working (when properly pressurized) doesn't mean that it was working correctly or at best efficiency if it's being pumped direct rather than primary/secondary on a multi-zoned system. You have a lot more boiler than your probable load, and that could be masking a world of system design ills.

"The pressure tank is now reading ~15 psi; he was a bit low. That part was easy."

Unless that number was tested with the tank isolated from the system with the water side of the tank fully depressurized it may not be correctly charged.

"I don't understand "open all the isolating valves anywhere on the system" at all. There aren't any valves except on piping below the boiler proper and a couple inline to the zones and the hot water tank, and they're all open already."

The pictures in your album shows no fewer than 8 valves in the near boiler plumbing, a valve for isolating the system vent, a valve at the circulator pump, some valves on the other distribution plumbing near the circulator pump. All but the one that looks like an outdoor hose faucet type handle, all appear to be ball-valves, and all have yellow handles. At the expansion tank there are a pair of valves with short yellow handles, one isolating the tank from the system, the other to a capped off host-fitting type port with a bronze cap. In the first picture the isolating valve is open, the port valve is closed. To test or set the pre-charge on the system, close the isolating valve, uncap the port and open that valve. You'll probably get a 1/4 cup of system water out of the port. With the port open it puts the system water side of the expansion tank at atmospheric pressure. Only then you can then test &/or set the precharge level on the air side of the tank.

When filling the system, the isolating valve to the expansion tank should be in the open position.

 

[TheFerretman]

Just because it's been working (when properly pressurized) doesn't mean that it was working correctly or at best efficiency if it's being pumped direct rather than primary/secondary on a multi-zoned system. You have a lot more boiler than your probable load, and that could be masking a world of system design ills.

I don't understand the words "pumped direct" versus "primary/secondary on a multi-zoned system".....I think it's the "pumped direct" part that I'm stuck on. The main recirc pump is a couple of feet downstream from the boiler. Can you describe what you mean here?

Unless that number was tested with the tank isolated from the system with the water side of the tank fully depressurized it may not be correctly charged.

Again I'll be testing this again this weekend when I've got more time, but I again suspect I was danged close to where it needed to be.

"I don't understand "open all the isolating valves anywhere on the system" at all. There aren't any valves except on piping below the boiler proper and a couple inline to the zones and the hot water tank, and they're all open already."

The pictures in your album shows no fewer than 8 valves in the near boiler plumbing, a valve for isolating the system vent, a valve at the circulator pump, some valves on the other distribution plumbing near the circulator pump. All but the one that looks like an outdoor hose faucet type handle, all appear to be ball-valves, and all have yellow handles. At the expansion tank there are a pair of valves with short yellow handles, one isolating the tank from the system, the other to a capped off host-fitting type port with a bronze cap. In the first picture the isolating valve is open, the port valve is closed. To test or set the pre-charge on the system, close the isolating valve, uncap the port and open that valve. You'll probably get a 1/4 cup of system water out of the port. With the port open it puts the system water side of the expansion tank at atmospheric pressure. Only then you can then test &/or set the precharge level on the air side of the tank.

Yes, there are many valves but I didn't know what you mean by "opening all the isolating valves" -- every valve is open (none are closed) except the short-handled ones by the bronze capped.

It sounds like you want me to close the larger valves and open the fill port valve, which is easy enough.

When filling the system, the isolating valve to the expansion tank should be in the open position.

This makes sense!



Steven in Colorado

 

[Jadnashua]

What you do NOT want to do is to use an automotive type antifreeze solution in your boiler, even if the main components may be the same. Various additives can be problematic, and could be a health issue if you ever get a leak either in a fill valve or between the heating circuit and the hot water tank.

If you do not have sufficient flow through the firing boiler, you can damage it. A primary/secondary loop design always keeps a safe flow through the boiler, and the secondary loop pulls off what it needs to perform it's job. Depending on the exact system setup, you might be able to safely get by without that setup, but it's not likely with a multi-zone system and the normally huge variations of load through the season.

 

[TheFerretman]

What you do NOT want to do is to use an automotive type antifreeze solution in your boiler, even if the main components may be the same. Various additives can be problematic, and could be a health issue if you ever get a leak either in a fill valve or between the heating circuit and the hot water tank.

No no no....this is pure propylene glycol, uncut. That's all that's ever been in the system.

If you do not have sufficient flow through the firing boiler, you can damage it. A primary/secondary loop design always keeps a safe flow through the boiler, and the secondary loop pulls off what it needs to perform it's job. Depending on the exact system setup, you might be able to safely get by without that setup, but it's not likely with a multi-zone system and the normally huge variations of load through the season.

There is a loop running through the hot water tank that would seem to act as you describe. It tees off the supply side and the return side and is pumped by a separate Grundfos. I don't know if there's logic in the boiler to turn that loop on/off to do what you're saying or not, honestly.

The gauge I bought was the wrong kind (too high a psi range) so it's basically useless for me. I'm going to have to go get a correct one at a plumbing supply store so I can confirm whether or not the pressure really is low or if it's just a bad sensor/gauge combo on the boiler.



Steven in Colorado

 

[TheFerretman]

Thought I'd post an update for folks!

As it turned out, the system was indeed low on glycol...or rather enough to keep the pressure up. The gauge on the boiler proper is a little bit sticky, but we put a new gauge on the system and it comes close to matching the boiler's gauge. It's nice to have two of them so I can cross check at least.

I had the system serviced by a tech from a local company called ABC Plumbing. They did great work; after checking the various manifolds for leaks we first aired up the expansion tank (it was pretty close from my earlier work) and then he put about a gallon and a half of fresh glycol into the system. Got the pressure right up and then we verified that all was working well by checking each zone and manifold. He pronounced all good and the system itself well designed.

He also recommended that I might want to put a glycol makeup system like this and it seems a goodly idea. A makeup system is apparently fairly common with most of their customers and it seems a reasonable solution (though I think they're more than a little overpriced for what's basically a tank and a pump). I'll probably pick this up in a month or so; if there is a leak it's a very slow one but this will let me stay on top of it without losing pressure and such.

I learned a lot out of this visit, more than enough to properly pressurize the system myself next time around if need be. Hopefully it won't of course with the makeup system.


Steven in Colorado

 

[Jadnashua]

If the system is installed properly, you should NEVER need a makeup system! Once first commissioned, the only time it might lose some working fluid is if something needs to be repaired and the system opened. Better to spend any money on finding leaks, however small.

 

[TheFerretman]

If the system is installed properly, you should NEVER need a makeup system! Once first commissioned, the only time it might lose some working fluid is if something needs to be repaired and the system opened. Better to spend any money on finding leaks, however small.

Yes, that's a nice theory and while there's certainly no way to prove it to you the system HAS been installed properly. There ain't a leak in it anywhere--I know, I spent the last two weeks going over every inch and manifold.

The make-up system will keep this silliness from happening again, and if the cost is a 5 gallon bucket of glycol every two or three years that's pretty danged small.


Steven in Colorado

 

[Jadnashua]

Assuming it did the normal thing of dumping some from the high pressure safety valve when the ET got low, you may not have a leak, but you'd never be alerted to that fact if it can automatically top itself off.

 

[TheFerretman]

Actually this is QUITE true and something I discussed with him. While we found nothing around the valve itself or beneath the discharge outlet, we did find evidence of some a very small, very old glycol leak from the fitting to the expansion tank. It was VERY slow -- the dried dribble didn't even get over the side of the tank to hit the floor. At any rate we took that off, cleaned up the fitting and top of the tank, and put it back with Teflon tape.

That might have been it, though it seemed older than what I would have expected. But it was something and I suppose might have caused the issue over time.