I am having issues with the hot water heating system in my tenants apartment.
Over time (about a week) she ill lose heat, and I feel the problem is air in the system. The funace will be warm (190 -200 degrees on the guage, and the pump will be running, but the return line will be cold), so I bleed the system, and normal operation returns. But it recurs. The question is why?
The set temp is about 190, but it appears that the actual shut off occurs a bit over 200, according to the temp/press guage.
I have tried to adjust the automatic fill valve, but either I haven’t gotten it right, or there is another problem. Any pressure over 30 results in seeping leaks from some valves (I’ll replace all valves and seals this summer) and the opening of the relief valve, which is indicated at 30PSI. When bleeding, I try to leave the pressure at 18 or 22 PSI, but when the furnace fires up, the pressure occasionally rises above 30PSI. Then even when it doesn’t, I return to no heat after awhile. The pressure reads about 15 at that point.
Here is a pic. (two posts down) I was under the belief that the vertical pipe on the right was the output, and the pump was the return. But in the close up shot note the label which is “Input” Is this device installed backwards? Does it matter? And what is it?
A possible symptom: I used to have a continuous drip from one of those little brass (air bleed?) valves in this system, but it stopped. There are two such valves in the system, one is pictured on top of the unknown item in the close up.
I installed the other furnace myself, (utilizing existing components) and it has basically the same design. It has been working flawlessly for a couple years now. This installation is by the previous owner.
Finally, the newest appearing component in the system is the gray pressure tank hanging off to the left.
I’m sorry to not have better information, but I will be happy to answer any and all questions should anyone have any suggestions. I can provide more pictures, or schematics if needed.
I can call my furnace guy, but the cost above and beyond his price is the loss of a day of work, and I would like to at least understand this system better myself before I call for help!
Edited 4/6/2004 5:36 am ET by LATEAPEX911
Replies
Jake--you better get the bandwidth down on those photos a bit in the future; a lot of us are on dial-up and can't want until the snow melts for the download to finish, LOL....
Run 'em through your photo editor and shrink 'em down to no bigger than about 400x600. That'll usually get them down to between 50 and 100 kb.
Sounds like you've got an air lock somewhere--have you checked all the bleeder valves at every radiator? and is it possible one of the HW lines has a 'trap' built into it by accident?
Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
Right! Sorry about the file size...heres a smaller version. I'll delete the above. They won't let me repost or edit other than to delete> ???
The radiators are all baseboards...slant fins. There is one loop that they are all on.
Maybe I should really go nuts bleeding....
thanks for the help!Jake Gulick
[email protected]
CarriageHouse Design
Black Rock, CT
You might try checking at http://www.heatinghelp.com
They specialize in hot water and steam heat. Have several books on the subject, Q&A's and a forum, The Wall.
Jake,
The device you're concerned about is installed backwards. It's called an Air Purger and facilitates the removal of entrained air. The manufacturers spec sheet states that the purger should be installed horizontally and as close to the boiler as possible. They must be installed so that water flows through in the direction indicated by the arrow (if there is one.) The vent on top of the purger automatically releases the captured air (or is supposed to.) It's not uncommon for the vents to clog over time, I've replaced mine several times over the last ten years.
The circulator is on the return to the boiler to protect it from the hotter supply side water (the impeller is plastic on most Taco circs.) So the pipe on the right coming out of the top of the boiler is the HW supply. The tank routed off the bottom of the purger is an expansion tank, normally prepressurized at the factory to about 12 psi. 30psi seems high to me; I maintain my system at about 12-15 psi cold, and it increases 5-10 psi when hot. Rarely does it reach 20 psi, and mine has to reach an air handler in the attic above the second floor, with the boiler sitting in the basement. If your pressure swings are extreme, you might want to check to see if the expansion tank is okay; too much in the tank when cold will create a solid tank when it heats up, negating the effects of the bladder and cause overpressure in the system. (The level in mine is about 1/4 full - from the top down - when cold. Level is determined when hot just by touching the tank.)
Also, I usually keep the auto makeup regulator valved out, as I have seen a few that leak by over time. A good pressure gage or two (and feeling the expansion tank) will provide any indication that makeup is needed.
The vent valve looks skanky. It should be replaced, and while you're at it (since you'll have to drain the system to replace it) install a small valve between the purger and vent so next time you won't have to drain the complete system.
The issue of venting is tough to diagnose from afar. Last fall I did some work for a couple that were having heating problems. It took forever to vent the system after I had opened it up to check on a few things. I finally found a piece of plywood wedged in the impeller of the circ. As long as the system has to be drained to replace the vent valves, you might want to pull the circ and check it. If it is the canned variety (motor and pump a sealed unit) pull the pump by removing the four small bolts on the pump casing. An o-ring provides the seal, though over time (and heat) this might begin to leak. A new circ is about $50-60 bucks.
The pic below shows the purger, tank and vent with a small spool valve for isolation.
BTW, I've tried to email you about the compressor, but no reply, everything ok?I never met a tool I didn't like!
Good pickup on the airscoop orientation. But I must disagree with this statement of yours
<i>The manufacturers spec sheet states that the purger should be installed horizontally and as close to the boiler as possible. </i>
The MINIMUM distance is 18" of horizontal pipe for an airscoop to function properly.
Walk Good
Phil
Wow, this is OUTSTANDING guys! Thanks!
Now I feel like I'm getting somewhere. I'm glad to hear that the thing I thought was installed backwards IS installed backwards, and now I know the name for it!
OK, so that will get replaced. And I too was suspicious of the "skanky" *(and thats putting it nicely!) air valve. I'll replace it as well. As well as adding valves. All good advice.
But a question. In your picture Nick, whats the function of the green thing? Is it a check valve? And I assume that the 90 degree lever valve is the one you're suggesting I add. BTW, nice basement..is that yours?
Also, Nick, I sent you an email. Try not to laugh [i] too [/i] hard!
Jake Gulick
[email protected]
CarriageHouse Design
Black Rock, CT
Edited 4/8/2004 2:18 am ET by LATEAPEX911
Jake, the green thing is indeed a check valve, it's usually installed to prevent reverse flow in the loop caused by natural convection when the boiler is running to heat domestic water, but no zone heat is called for. But with zones valves that open only when heat is called for, I don't see the point, but maybe someone else has a better explanation.
Indeed the basement is mine. You can take the remodeler out of the power plant, but you can't take the power plant out of the remodeler. After 25 years operating systems of all sorts, I went a little overboard when we installed a whole new heating/cooling system 10 years ago. Helen and my daughter needed better air purity due to allergies, so I teamed up with a HVAC company to come up with a hybrid system; heat pumps for each story, and a boiler backup system. Although I was told the HPs would kick off below freezing, I found them both running at almost zero out the first winter, so I pulled the schematics, figured out how the whole thing worked , and rewired it so the pumps now do shut off when the outside temp detector hits 32. I also wired it so it can be flipped back using 4 DPDT switches, and a jumper.
I designed the boiler monitor panel to tell me that 120 and 24vac power is available, when there is a heat demand signal for either zone, when each zone valve is actually open, when the circulator and burner are running. Over the years it has provided all i needed to know to diagnose a zone valve failure, a circulator failure, and two instances of where the burner was supposed to be on, but had tripped. The HVAC guy gets $100 just to knock on my door, so I wanted to limit the calls.
The Heat pump panel tells me what going on with the Humidifier, condensate pump, air handler and heat pump. Two years after installation, I found the condensate pump had quit and a pool of water spreading in the basement. So I wired the H/P and humidifier through the high level c/o switch of the condensate pump, so in the summer, the h/p shuts off if the condensate pump stops working (condensation on the coils) and in the winter the humidifier solenoid shuts if the condensate pump fails. (It's based on heat demand, and sometimes when the HP goes into defrost cycle, it becomes a clattering relay race, a design flaw I'm too lazy to fix.)
The Inventory panel and system came about when I had to change the circulator in the middle of a snow storm (ran out of fuel, to boot) so while Helen was out at the gas stations filling cans with kerosene, I had to dump the contents of the heating system on the basement floor. Because of the attic air handler, the system is filled with antifreeze. So I designed and constructed the system and controls. Had to use it once, so far. The poly tank (unused gas tank from a boat) can hold the entire contents of the heating system. The mimic on the panel allows me to see the flow path, as each ball valve has its own limit switch. It's overkill, I know, but I've made enough mistakes operating plants to know the value of a good visual aid. With a pump that can draw from either the tank or boiler and pump it back to either, I wanted to ensure the lineup was correct before use.
The PVC pipe to the left of the main tank is a chem add tank where i add antifreeze. Filtered water is added to the tank via a solenoid that is wired thru a high level float switch in the chem tank, so I can't overflow the tank. (The float switch also triggers an LED alarm on the panel, in case I forget.) I still have to add another line back to the main tank and solenoid valve to the high point vent so I can fill and vent the system without spilling a drop. Then I'll have to add more to the mimic, another relay, wiring, and on and on. Is this great, or what?
Sorry for the length. I never met a tool I didn't like!
Wow....what can I say? I feel so insignificant!'
Jeez, I knew that furnace of mine was a mess, but now I have posted on the net next to yours, the most impressive heating system I have ever see!
Actually, that was very educational! And i understood some of it!! What a killer system!! Did you tell Helen you got a great deal on all the fancy stuff due to your "contacts"??? ;)
Now, have you installed the feedback and control system that reads out the temps of the different zones on you cel phone display?
(I used to install and program home automation stuff, and remote HVAC control was a very popular option)
The system of mine that were discussing has an amzing number of zones: One! And no domestic hot water. Perhps the valve isn't needed then? But it won't hurt leaving it will it?Jake Gulick
[email protected]
CarriageHouse Design
Black Rock, CT
Air scoop does appear to be installed backwards.
You would have less trouble with air if the system was setup to 'pump away' from the boiler, meaning placing the pump on the supply side.
Consider installing a bleed valve near the highest baseboard in the system to speed initial purge.
System pressure of 12-15 psi is normal, unless structure is very tall.
Edited 4/7/2004 9:49 am ET by csnow