Air in boiler feed water

hot_rod

I don’t think you can get to the actual needle valve in that sep, that is where the air/ water stops?

pedmec

why don't you post pics of the install so we can see what it looks like and find the areas that are not correct.

DIYorBust

@pedmec thanks! I already did this in my other post and we had a lively discussion about it. So this time, let me make some of the changes that have been recommended here and I'll post some new photos.

Now I procured the 20 gallon expansion tank, and it looks like it might be overkill. Easily the size of an elementary school child, I felt confident driving in the HOV lane with it in the passenger seat. I think I do have a spot for it in my small boiler room. I checked the air eliminator, and it was not a spirovent! Although we had specified a spiro, it appears the installer chose to use a honeywell supervent instead. I think I will rebuild the supervent, but I haven't been able to find the core for sale, I suppose I'll have to contact honeywell, or just buy a supervent. They do sell the float unit. However, since the core is accessed from the bottom of the supervent, I'll have to attach some unions or something to make it accessible for cleaning if I install the makeup water supply and floor mounted expansion tank into there. Yes the 20 gallon tank seems a bit excessive, but we are installing steel column radiators, and generally the goal was to oversize the units so we could run the boiler temp lower. Nevertheless, we have been unable to gauge how much water is in the system, and this will help eliminate pressure variation as as the source of our issues keeping the top floor convectors from becoming airlocked.

DIYorBust

Update: Ok so the supervent rebuild kit arrived yesterday. It took a few days to get one, in the mean time I placed a caleffi minical in the top port on my dirtmag on the return side of the primary loop. Newer models don't have this port I believe. It seemed to help a little with the frequency of the boiler shutting down. Yesterday I installed the rebuild kit on the supervent air separator, feeling this could really be the ticket. The kit includes only the float and valve, and does not include the core, which is accessed through the bottom. I did not open the bottom yet, since I plan to install the makeup water and expansion tank there in the future, and the core could not be replaced. At one point I was able to hear the rebuilt supervent releasing a little air, but only once, it was the air that was admitted when I drained that small section to rebuild the vent. I could not find anything obviously wrong with the old component. The float was in good condition, and there was no buildup of muck inside. But as hotrod said, the valve mechanism may have been damaged.

My excitement was somewhat tempered when after a little while I got the glug glug glug, boiler temp spike, e001. One time, before the rebuild, I had the boiler shut down have glugging. Now annoyingly, the boiler seems to kill power to the primary pump when this happens, so it can be tough to get the air out. Some options are using the flush ports, or running the boiler briefly with the gas valve shutoff. One time, I really struggled to get the air out, but after a few minutes of trying things, starting and stopping the pump, purging, etc, the autovent on the top of the boiler hissed for a good 60 seconds or so. That is a lot of air. I'm still confused as to how that much air could be getting in. I have not drained down the system recently and am trying to avoid that another month or so until the weather warms up and mitigates the freeze risk. A leak that big we'd surely see the water somewhere. And keeping the pressure over 20, we really shouldn't be pulling in air. I have not drained down the system recently and am trying to avoid that another month or so until the weather warms up and mitigates the freeze risk. Perhaps I just need to run the system a couple days after the supervent repair vent to clear it out?

Grallert

Is there not a way to do some backwards math to find the volume of your radiators by using the sizing charts available in "Every Darn Radiator" After all that's how they originally determined the steam capacity. I think.

DIYorBust

Ok let's take a shot. I have 5 steel column radiators in at the moment. They are on average about 4000 btu at delta T60, so lets round up to 5000. That's about 25kbtu of column rads. We also have four cheaper baseboard convectors, maybe around 15 feet tops, so lets call that 10kbtu a piece. Now let's use this chart on page 41 which I found referenced on this forum:

https://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2013/02/TEH-1196B.pdf

So we've got maybe 3 gallons per column radiator assuming the largest number from the chart, and then maybe .4 gallons for the non-ferrous baseboards. So 3 gallons/radiator * 5 radiators + .4 gallons per baseboard * 4 baseboards = 15 gallons + 1.6 gallons = 16.6 gallons. Now there's also the piping and components, so lets add what another 10 gallons maybe? 26.6 gallons. Now to the wessel calculator mentioned by hotrod(see below). We see that such a system recommends a tank around 5.8 gallons. With a #30 and a #60 tank, I should be roughly okay with about 6.7 gallons. This is assuming we can only tolerate a 5 psi increase in pressure, so we might have a little room. However if I add more column radiators, it sounds like I'll need a bigger tank. The 20 gallon monster is here just waiting to be installed. But for now, why can't I seem to get the air out?

hot_rod

No harm is having an over-sized expansion tank. Assuming it is properly adjusted form the intended fill pressure, 20 psi in your case.

Has the pressure relief valve ever discharged? If not you have not hit 30 psi or more.

I wonder if air trapped in all the column rads keeps making it's way back to the boiler and bubbling at the top of the boiler HX.

If you have any ups and downs in the piping it can be a bugger to purge without a high volume purge pump. With large diameter piping, a 1/2" fill valve may not allow enough flow to get an adequate purge.

Most hydronic guys, and gals have at least a 1/2 hp pump for power purging systems. GEO loopers and people that work on large piping systems sometimes build a tank with a 1 or 1-1/2 hp pool pump to blast 20- 30 gpm through large pipes.

Simple homebuilt rigs have a pump on a piece of plywood across the top of a large, heavy duty plastic garbage can.

I built this 24 gpm cart with parts from online, a Grundfos CM-5 120V pump, 1" hoses.

It just feels like you are not getting an adequate purge through all the piping and radiators.

DIYorBust

Yeah that makes sense. The radiators do have bleeders, some auto, some manual. I'm not getting a lot of air in at the bleed valve. By the way, I see you're a trainer for caleffi. I'm trying to get some 504401 AERCALS for my radiators, which are sold for the US market by hudson reed. Is there any way I can get them direct, since it doesn't seem they stock them here?

That rig for purging is cool, but it's way over budget for me. Would connecting a hose to a valve closer to my water service line do the trick? My heating system is mostly inch and a quarter. But also keep in mind that I did not have this boiler air issue until relatively recently. The system has been in use about 8 years.

Regarding the tank, yes I did have an issue that I posted about in my other thread a few years back. I was finding my top floor baseboards were often becoming airlocked. If I increased my pressure, I'd get discharge at the relief valve. The installer had only one amtrol #30. I added the #60, and it seemed to improve things, and I added the minicals to the baseboards on the top floor only, and then I didn't have to bleed the radiators all the time. In ret rospect, it's possible the pressure was high enough, but air from somewhere else was migrating up into the top floor radiators. I don't know. It's not like I didn't try to get all the air out, it just never seemed to work without the auto bleeders. With my current setup, the top floor baseboard does not become airlocked, and the relief valve does not open. I do suspect a large expansion tank could help, particularly since I would like to install additional radiators and may want to replace some of the baseboards.

hot_rod

https://forum.heatinghelp.com/discussion/comment/1849304#Comment_1849304

I have had folk tell me they use online UK sites to order Caleffi Euro products. Altecnic, www.altecnic.co.uk is the official Caleffi rep in the UK, they have a where to buy section.

The 504 is a straight thread with the hemp knurling. I have one and it does go into a NPT, but you would want hemp or Loctite 88 thread to install it. As you see in the pic the threads go all the way into the FIP NPT.

It is a nice radiator air vent fitting, it creates a large chamber up high for air to find. I brought a sample in to try.

DIYorBust

Ok so I've had the rebuilt supervent in there over the weekend, so about 3 days, and also the minical on the old dirtmag. I still had about 4 e001s, about 1 per day, but it was less frequent than it used to happen, and just resetting the boiler got it going again, I didn't have to do any purging routines. However I also note that with the warmer weather, the boiler runtime for spaceheating was probably less. Another observation I made is that the problem often happens when the system switches the zone, such as when the DHW indirect tank calls for heat on priority, or when it finishes heating the indirect and switches back on the space heat circulator. The system has only one primary pump, there is a way to pipe it so that a second primary pump feeds the indirect loop, but the installer did not want to do it this way, probably because it would have required customizing the primary loop manifold. I do still hear some air in the pipes with the space heating zone is on.

When the system shuts down for e001, the primary pump shuts off, but I believe the circulator keep running. That's because the boiler controls the primary pump, but a taco zone controller controls the zone circulators. Is there any hope the supervent just needs more time to work?

hot_rod

A day at the most to get all the air out, assuming all the radiators and indirect have had flow through the separator?

In some cases adding another sep to the indirect circuit can speed up the air removal.

It really should not be this difficult to get a 100% air free system with the parts you have.

Maybe some pics may show something we are missing?

DIYorBust

Guess what! I've been running 3 days now, no E001! I can still here air in the pipes, but it's not as bad. Have not drained down the domestic side recently. Boiler runtime has been reduced a bit by the warmer weather, but it's still been running a decent amount, particularly at night. I think hotrod may be right that there is air at high points. It can't be a fully airlocked section, because all my radiators are warm. Need to consider whether to use a purge pump. I'll keep tinkering and come back when I find something. Thanks!