Hi, I've had this system for about 15 years and am starting to have problems. It is actually a two part troubleshooting question.

First, I don't know how the air purger gets the air out of the system. Do I need to depress something to purge any trapped air? I noticed that the cap on top of the system is oozing water out the top of the "valve" very slowly. Is this common? I don't see any air bubbles mixed in with the water. Is this the way the system is supposed to purge the air from the system? Should the cap be left somewhat loose or should it be snug?

The second part seems to be related to the circulation pump. I'm not sure if the circulation pump is working properly. It's a Grundfos UP 15-42F pump and it is getting power according to my tester. My heating system seems to be working (maybe not at the best efficiency) but hot water tank does not seems to be recovering properly. The inlet pipe side is hot but the outlet side is cool. If the system is left alone long enough and the boiler come on periodically it seems to heat the water. Sometimes it seems to heat the water just fine but other times it takes many hours. Any ideas? How can I verify if the pump is functioning properly? Can I take the cover off the circulation pump?

There are four bolts on the pump (one on each corner). If I loosen these will this expose me to the boiler hot water?

I've taken some pictures of the system and I'd like to include them for reference but I see that I'm not allowed to add attachments at this point.

Thanks

 

Hello and welcome,

As far as the air purger is concerned, it just routes the water and forces the air bubbles to come to the top where the Hi-vent is to release the air.
The hi-vent is just a bowl with a float and a valve. During operation the float is normally keeping the valve closed. As air is introduced into the vent bowl, the float lowers, opening the valve to release air only. Then, once purged of air, the float will return to normal status and close the valve. The cap is there so you can direct the air and not get spitting on the ceiling and should be loose. If the vent is leaking you can close the cap until such time as you can replace the valve, but you will have no air purger during this time.

Usually when they start to leak it is caused by dirt.
Sometimes removing the cap and depressing on the top (be prepared to get a little wet) will move some dirt and then be OK, but very rare. Some brands can be taken apart and cleaned but once again, sometimes not worth it. Most often the best cure is replacement.


Now for the Grundfos circ pump, I went to Grundfos's web site to look up info on your exact pump and after 1/2 hour of searching a useless web site I gave up so I will have to wing it from experience. Unfortunately for you, where I live the industry standard in this area is Taco cirulator pumps.
I have run across a few grundfos pumps occasionally.
All I know about grundfos pumps is usually there is a way to manually spin the pump, by taking off the quarter sized cap in the center of the pump. then taking a screwdriver and spinning the pump. You may get a few drops of water but when you put the cap back on the o-ring will seal it.
Also check and see if you have a multiple speed pump. If you do try changing the speeds and see what happens.

If the pump appears to be pumping I would then start looking towards air in the system. You will need to purge it out as the air purger is only there to get out small quantities of air. If an air bubble has occurred in the zone someplace it must be mover, or purged out or the pump cannot move the water.

Yes, removing the bolts on the pump or the hi-vent will require the draining of a certain amount of water and pressure from the boiler.

Well this is a good start.

 

Thanks so very much for the advice. It makes much more sense the way you have explained it.

The air purger system is exposed to a fair amount of dust and dirt. I'll try this evening to release a small amount of water thru the seat and see if that fixes the slow seeping problem. As you stated though I will not get my hopes too high.

The Grundfos web site was almost a total waste of time. I did find that my pump is a single speed pump and that you could somehow rotate the shaft to purge some air. They did not explain how but your explaination makes sense (I'll also try that this evenung). The web site also gave me an ideas of what it would cost to replace the pump (approximately $250 plus shipping).

Again this morning, the hot water tank was completely up to temperature. I had checked the system before going to bed last night and noticed the thermocouple on the hot water tank had opened the boiler valve asking for hot water to bring the hot water tank up to temperature. I monitored it for about 15 minutes and did not detect any warming on the boiler return line. Therefore, I assumed that the boiler water was not moving rapidly thru the system (it would again be a while before the valve would close). Sure enough the valve was closed this morning indicating that the hot water tank was up to temperature.

Anyway, I'll let you know the outcome what you have suggested.

Thanks again

 

To post pictures you need to first upload the pictures to a photo hosting site such as photobucket.com or villagephotos.com. and then post the public URLs for the pictures (or album) here.

As for how the American air purger works...mostly they do little or nothing. As Plumingods stated they can only remove a small amount of air but only if they are plumbed correctly. The air is released by an automatic air vent on top of the purge fitting and what Plumingods described is the most popular type of vent but there are other types and some are even less successful in eliminating air.

The first thing you need to tell us is what is the pressure in the boiler system. It should be between 12 and 15 psi when the boiler is at room temperature and between 15 and 27 (absolute maximum) when the boiler is hot.

Does this system have a single circulator pump for both space heating and the water heater? If yes, then what type (manufacturer and model) of zone valve is used to the water heater?

Post the pictures and it will help. More pictures are always better than fewer and they need to be clear with both close-ups and some from a distance so that we can see how all the pieces are plumbed together.

 

$250 !!!!!The pump should only run you about $60-$75......I get $250 for a service call to replace a circ and purge the system...you don't need to use that exact model #(UP 15-42 F) a Grundfos UPS 15-58 FC has a pump curve very close to the 15-42.I might even use a Taco 007..The only reason I install Grundfos pumps is that they carry a 3 year warranty where Taco only has a 1 year

 

To All - Thanks for the excellent advice and helpful hints.

Since my last post, I've learned more than I ever wanted to know about my system. As mother nature or Hoyle would say "if it's not broke don't fix it". Well, many things happened during my repair session. First I tried to free/clean the air pruge valve but that did not work and made things much worse since I now had spurting water (cold water) coming from the purger valve. I shut off the water supply and replaced the purger valve. I wanted to make sure it would not leak after installing the new part so I reopened the supply line and found two new problems, The downstream shutoff valve from the pressure regulator did not function and the pressure regulator did not seem to function properly (always applied line pressure to the boiler). At this point I knew I was going to introduce a rather large amount of air to the system since I would now needed to drain everything up to the next shutoff valve (which is just before the air purger). I replaced the faulty shutoff valve and installed a new pressure regulator. This corrected the boiler pressure problem and I now have a functional shutoff valve downstream of the pressure regulator. I very, very slowly opened the shutoff valve below the air purger and let that set for an hour or so. I then brought the system up to make sure there were no leaks and see if anything had changed (I wanted to know if anything I had done so far corrected the original problem). After bring the system up to temperature and pressure I still was not getting circulation through the system like I thought I should.

I had to let the system cool back down and try to replace the circulation pump. Yes poorplmbr was correct that the replacement pump only was $100 (with tax). The higher price was from Grundfos website and included the price of their mating flanges. I had a supplier in town that carried the exact same pump so I purchased that model. It came with o-rings but unfortunately did not fit the system. The plumbers that originally installed this system obviously did not use Grundfos mating flanges because the supplied o-rings slid right over the mating flared pipe. The mating "flange" was a 2 piece construction that used a rubber gasket the shape of the entire Grundfos flange. By now, all stores were closed and I had to wait until the next morning to finish the job. I purchased a square piece of rubber and made my own gaskets.

The system now seems to be OK and is functioning fine. I now have rock solid water temperature and the heating system work OK. The only thing I've not done is bleed the system. I have not heard any air (bubbles) flowing through the system or pump. I did purchase the bleeder turn key to do that step but so far have not had a reason to.

For other questions that were posted, the pressure on the boiler seems to be 15 to 17 psi before the boiler kicks on. The pressure goes up to 25 to 30 psi at maximum boiler temperature (I don't think it is quite 30 but it's a little hard to determine the exact pressure given the loaction of the pressure gauge).

The system has a single Grundfos circulation pump.

The zoning valves are all the same for space heating and water heater and they all seems to be functioning properly. The name brand I don't know. I'll check that when I go home this evening.

Thanks you all again for the advice and helpful hints.

It's been an experience for sure.

 

Sounds like you may be in for an expansion tank soon also. On a normal system with a properly sized and charged expansion tank you should only see about a 2-5 lb difference from start.

 

Mark,

You say that I may be in for a new expansion tank soon.

Let me ask you a question about the pre-charged tank. Is it possible to loose the charge or is this supposed to be a sealed component (do they have an internal bladder)?

The reason I ask is that when I released pressure from the entire system I drained off about a gallon of water or so from to reduce the entire system pressure to zero. I suspected that all that water was coming from inside the expansion tank. Should I have done something differently? Should I have added air to the expansion tank and pre-charged the system to 12 psi before re-introducing the water supply?

So far, no additional problems that I'm aware of.

Thanks
Paul

 

If you have a large tank that is up in the rafters horizontally, you probably have an old style tank without a bladder. If that is what you have there should be an isolation valve so you can drain it without disrupting the rest of the heating system.
And you will need to loosen a plug on it someplace so it can suck in air while the water is draining out. Drain the tank completely, close plug then open isolation valve to refill. It will allow some water back in but will leave a good air charge at the top of the tank.

The newer style tanks are about 14" round and 16" tall (depending on your need). These tanks have a bladder in them to separate the air from the water, but they can go bad or you can lose air pressure and the tank will fill up with water. There should be an air fitting on the bottom of the tank to check the pressure.

If you let a gallon of water out I am going to say you have an older style tank. It should be drained and reset each year when the system is serviced for the winter. Or replace it with a new style.

 

Mark,

From your description, I believe I have the newer style tank plus looking closer it states that it came precharged at 12 psi. Therefore, I'm assuming that it should have a bladder (or at least had one at one time).

Now for the amount of water that I got out of the system when I wanted to reduced the system pressure. All the zoning shutoff valves were closed and I guess I could have shutoff the valves above and below the circulation pump but I did not. This left the air purger, boiler, pump and "T" to the pressure regulator shutoff in the isolated section. From that portion of the loop I got about a gallon of water. Sure sounds like the bladder is probably shot on the compensator doesn't it?

My immediate concern is that I will be out of town for a few days and I want to make sure things will be OK. I don't want to get a call from home that the system busrt a pipe or worse.

If I can't get to this in the next week or so do you think it will be OK? At what boiler pressure should I get concerned?

Thanks,
Paul

 

I think I misunderstood where you took the water from.
I thought you took it from the tank, so as long as the tank has 12-15 psi of air in it, the tank should be ok. If you drained water from the air valve at the bottom, you will need to replace the tank, otherwise I think you should be ok. But make sure to check the tank pressure because the tank can lose air but not penetrate the bladder so you will get no water through the air valve
. If that happens the tank will fill up with water, but will not leak by because of the bladder. And it will be like having no tank at all, which will cause your pressure to go to high and blow off your relief valve. Only a few pounds of air can cause this to happen too.

 

I hope Mark don't mind if I clarify this a bit.

A bladder type tank WILL lose air at the rate of perhaps a pound or two a year. The air 'migrates' through the bladder. (ever wonder why a balloon deflates in a few days?)

IF the tank is installed with the air valve pointing DOWN, and you get ANY water out when you depress the valve, the tank is shot and needs to be replaced because the bladder is leaking.

If the tank is installed in any other position, this test is inconclusive. If you get water out the air valve, the tank is shot, but it is possible if it's installed with the air valve pointing up or sideways that you won't get water, only air, even IF there is a leak in the bladder.

The first thing to do is to check the air pressure in the tank, before condemning and replacing it.

To check the air charge on the tank there must be little or no water pressure on the water side. If there is, you will get erroneous readings on the tire gauge.

Yes, a tire gauge. Relieve pressure from the boiler by closing the water feed valve and opening a drain. You won't need to drain much, just enough to see the boiler gauge go to zero, or very close. Using the tire gauge, check the air charge in the tank. It should be 12-15 PSI. If it's not, use a small compressor or bicycle pump to add air to the tank.

With the air charge correctly set, re-pressurize the boiler. You said that when the boiler is cold, you have 15-17 ? Unless your house is taller than 2 stories, you can run the boiler at 12 PSI. Re-adjust the feed valve to 12 PSI.

It's also possible that your boiler gauge is not accurate, but assume for now that it is.

There should be pressure RELIEF valve on the boiler that will open if the boiler pressure goes over 30 PSI. There should be a pipe on that valve leading down toward the floor or a drain. This relief valve is to prevent the pipes or boiler from rupturing due to too much pressure. I would start to get concerned about the pressure if I saw it heading toward 25 PSI. My gut says that re-charging the expansion tank will take care of it.

 

All,

My system must have a bladder. I tried what NJ Trooper suggested and Yes my expansion tank is mounted vertially and air valve pointed down. I placed a bucket under the air valve and depressed the relief valve and got only air.

At the time I tried the above, the boiler temperature was 175 Deg F and the pressure was just under 20 psi. If I have time tomorrow, I will isolate the boiler again and relieve the pressure. I will then take a pressure reading on the expansion tank and let you know the tank pressure.

My home is a two story structure. You said that I could adjust the water feed valve to 12 psi if need be, how would I do that?

Yes there is is pressure relief valve on the boiler which I have a bucket under to see if any water/vapor is escaping. I'm assuming that if the pressure relief valve is triggering then it will probably be steam since the boiler temperature would be around 220 deg F at that time. So far, things look OK. If it's releasing, it's while I'm not in the basement and these days I seem to be spending a lot of time in the basement.

To catch up on an older question that was asked about the zoning valve manufacturer, they are all White Rodgers - Zone-A-Flow Water Valves.

The expansion tank is a Amtrol Extrol Model 30 Precharged to 12 psi {Max W.P. = 100 psi} Date Code 11213893.

Thanks to All,
Paul