5 zones, 1 with major issue. HELP

creativeinstalla

I am the GC on a job we installed 2 years ago.  5 zones.  1 is turbo max, 1 controls lots of radiant, 1 basement baseboard (old existing zone), 1 st floor, mostly new baseboards, and 2nd floor - we added 1 room on to loop.  All were working fine except the 2nd floor.  the pump kept loosing prime.  We and our lumber have been back a few times.  installed a Spirovent on that zone immediately after pump (all pumps are pushing) ,  Installed flow checks on both sides of the loop (after spirovent and on the return before it ties into manifold)  this is Zone 1 on the header.  Every time we went when customer called zone was calling and pump was on.  No water circulating.     Today - I just bled out about 1 -2  gallons of water and then it starts to fully circulate.  We are all at a loss at what is causing this.  the boiler was running at 20LBS when hot.  i pushed up to 25 today.  house is 2 story with boiler in basement.   We 2  #30 expansion tanks.  Pressure relief valve has never blown off yet.   Any ideas on why this zone keep s getting stuck.  Have changed pump 3X and it is probably not defective,  Have a 010 Taco on there now.  Please help!

Mark Eatherton

Got pictures????

That or a good sketch of the installation would be extremely helpful..



ME

World Plumber

Direction

I saw that once when one pump was going the opposite way. Once another zone came on with that zone, that zone wouldn't work anymore.

MC

Jean-David Beyer

This will probably not solve the problem, but..

the Spirovent should be in a high temperature, low-pressure area, not high pressure, so it should be before the circulators, not after. Also, 20 pounds pressure seems high. You need 0.434 psi per foot, with perhaps an extra 5 psi pressure, so for a two story house, 12 to 15 psi should be enough. Where is th expansion tank with respect to the circulators? Immediately before them?

icesailor

second floor issues:

All zones have their own pumps? The second floor has its own pump? What special circumstances require a 010 pump? Is it Baseboard? Baseboard isn't high head. If it is baseboard, and not high head, why did you use a 010 instead of a 007? I've seen 007's push a lot of water around some rather large heating applications. I've never used a 010 pump but I've seen a lot of them used where I never would have used them. And there were problems. But I tend to let the sleeping dogs lie.

I think that if you have baseboard and a high head circulator with low resistance, you are getting cavitation in the 010 pump impellers and the air is ending up in the second floor zone or some low spot in the piping.

I ersonally think that it is better to have a pump that "barely"works than one that works too well, then doesn't work. Either that, or there is debris in the piping causing an obstruction and you get cavitation at the obstruction.

A train or experienced eye needs to look at it.

Jean-David Beyer

I've seen 007's push a lot of water around

I have what I consider to be a very small house; two zones. One zone needs 6463 BTU/hour when it is 0F outside, and design day temperature around here is 14F. The emitters up there are two pieces of 14-foot Slant/Fin baseboard supplied with water that never exceeds 134F. I put that much baseboard in so I could run it at lower water temperatures (condensing boiler).



There is about 70 feet of 1/2 inch copper tubing, 30 feet of 3/4 inch, and the 28 feet of Slant/Fin. I figured that was a lot and was wondering what size circulator to use. I wondered about an 0010, but then I got John Siegenthaler's design studio program, and it seemed that an 005-IFC (2.3 gallons/minute) or an 007-IFC (2.4 gallons per minute) would be enough. I did not tell the contractor what to use, because I was still trusting his company at the time, and that was their job. They just used Taco 007-IFCs for everything. Now the pipe lengths above are just estimates, because I would have to rip up the floors to find out the exact numbers. I do not have flow meters, so I do not know the real flow rate.



Now I guess the flow rate is a little too high. I get enough heat in that zone at all times, at least down to 9.6F outside, by actual test. But the temperature drop along that circuit is very low. Yesterday, when it was 35F outside, it was putting 123F water in there and getting 122F water back. Makes the heating pretty uniform, though. ;-). I do not hear water rushing around so flow must be less than 4 feet per second. So a Taco 007 certainly has no trouble pumping water around my second floor zone.



"A train or experienced eye needs to look at it."



Yes, and an experienced ear too. Can detect air and cavitation.

I just had a noisy 007-IFC replaced. The technician then purged that part of the system, but there were a few bubbles remaining, so I now know what air sounds like, both at the circulator and in the  baseboards. The air eliminator eliminated them by lunch time. It is funny to hear the vent valve release the air as it went through the air eliminator. I still do not know what cavitation sounds like, but I can guess.

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icesailor

Issues of Flow:

Well, everything seems to have changed since I learned about it but in old gravity systems with those great big 3" and 4" steel threaded pipe mains etc, I understood that the whole idea was that the water flowed more or less at 1 gallon per minute through the system. 1 GPM equals 500# of water per hour. I thought thatSlant/Fin rated their baseboards at 1 GPM (500# PH) and at 4 GPM or 2000# PH. It is rated at 20 degree drop. In other words, if the water flows in at 180 degrees and flows out at 160, that the heat emitter is emitting the rated amount of heat and the flow is correct. If the water went in at 180 and came out at 170, either the heat emitter wasn't emitting the proper amount or the water was flowing at more then 1 GPM. If you use a small pump and the return water is 150 degrees (30 degree drop), the flow is too slow. If you change pumps and the drop goes to 170 degrees, the pump is too fast. But that is deceiving. Because if the emitter is emitting at its rated outlet temperature, the drop isn't important. That just means that there is more for the next emitter/zone. You must know how many GPM's are flowing. Guesses don't count.

Some have the idea that this low temperature water system is the holy grail of heating. Maybe it is. Any time I have seen low temperature water systems, some of the people didn't seem warm. The suggestion of wearing sweaters didn't go over well. Turning up the system temperature made everyone happy and me a hero.

Your system sounds to me like it is whacked in the head. Keep it simple but don't be stupid.

Jean-David Beyer

whacked in the head?

Why do you say it is whacked in the head? It always produces enough heat, so I have at least as much emitter surface as I need at the water temperatures I supply. It runs at a low temperature, so I get as much condensing as I can expect (it condenses all the time unless it gets below the design day temperature outside). The only thing unusal is the low temperature drop, but why does this matter if the flow rate is not causing problems (greater than 4 feet per second)? The amount of heat rejected into the room depends on the temperature difference between the air in the room and the temperature of the water in the baseboard, not the temperature drop. Aside from noise and cost, I would think one would run the water as fast as possible, getting minimal temperature drop. Of course there would be some, but if it is less than one degree, I cannot measure it, so I say it is none.



If the system did not heat enough, I would have to increase the length of the baseboard, or increase the water temperature, but it does heat enough. I am not forced to wear sweaters. I see little point in putting in a smaller circulator just to get more temperature drop in the circuit.



What am I missing?

icesailor

A forest in the trees:

One of us is confused.

The way that heat gain/loss is measured is by how much heat is gained/lost in its travels. If 1 BTU is the amount of heat energy needed to raise 1 pound of water, one degree, then it takes 10 BTU's to raise 10# of water, 10 degrees. It takes 10 BTU's to raise 10# of water from 120 degrees to 130. It also looses 10 BTU's if the water temperature drops from 130 degrees to 120 degrees. A gallon of water weighs 8.33#. The weight of water flowing at 1 GPM weighs around 500". It takes 10,000 BTU's to heat that water and it will loose 10,000 BTU's in that hour. I guess, at a 20 degree drop. If the water flows at 2 GPM and the water temperature drops only 10 degrees, it still looses 10,000 BTU's per hour. I guess if you slow it down to 1/2 GPM or 250# per hour, it had a 40 degree drop. Or something like that. The only way you make up for it is through increased length/amount of emitters. If your rooms get warm, what is your problem?

You spend THOUSANDS on "stuff" so you can run your equipment at lower temperatures so you can save a dime. "Spend ten dollars to save a dime".

If the house is warm, what is the problem? If you get the thing too cold, you will wreck it. The jury's out on this stuff as far as I am concerned.

When they have computer controlled combustion, tied in with the load on the system that will modulate the water with the outside and inside temperature, it's just doing research.

And when you get done pricing a hydronic system, with all this fluff on it, it is EXPENSIVE. Then, they go get a price on Scorched Air. Nothing modern about that. And Scorched Air gets it again. Because over priced, over engineered and over installed systems will loose every time. I used to give two prices One regular and one with the fluff so they had a choice. Now, it's the good system with good basics and an estimate on the fluff. I haven't sold a lot of fluff.

Jean-David Beyer

One of us is confused.

Maybe both. Or we are talking about different things.



How much extra does it cost to run 28 feet of Slant/Fin to use 120F water instead of 180F water? I could use about 17 feet less. Since we must not talk price here, my recollection is that to put in the Slant/Fin  was less than 10% of the cost of the entire job. It was about half the cost of taking out my in-ground oil tank. I looked up the price on Pex Supply and the price of the baseboard was less than half the price of the labor to put it in. Since each piece was a simple straight piece, I imagine the labor would have been the same, whether they put a 5 foot piece or a 14 foot one.



If I run the boiler at 180F, it might run at 85% efficiency, where at 120F it can run at about 90%. I used about 120 therms last January, and perhaps 20% went to heating my upstairs. So if you knew what I paid for the extra Slant/Fin, and what I pay for gas, you could calculate how much I save with the extra baseboard, and compute how long it will take to pay for it. I would have to save about 200 therms. I won't save it in one year, but it will probably not be more than 10 years. I do not think you can charge the extra cost of a mod|con boiler because most of my heat load is in the radiant slab at grade zone downstairs, so I would have gotten that anyway.

LarryC

Minor math error

Ice,

 

I think I noticed a small math error in the following staement.

 

"If 1 BTU is the amount of heat energy needed to raise 1 pound of water, one degree, then it takes 10 BTU's to raise 10# of water, 10 degrees."

 

I believe it should be

"If 1 BTU is the amount of heat energy needed to raise 1 pound of water, one degree, then it takes 10 BTU's to raise 1# of water, 10 degrees."

 

As originally stated, it would take 100 BTU to raise 10 # of water 10 degrees.

icesailor

Mistakes: Major Issues:

I make lots of math mistakes when I do them in my head,

I think that the concept is correct.

I think it is fine to over radiate as long as someone is willing to pay for the extra radiation. And as long as a proper heat loss is done and the boiler is sized to the structure and not the installed radiation. Unless the planned water temperature is used. Fine. I just think the next step needs to be taken. That the water temperature needs to be set UP when the room temperature goes down. Like it does when the outside temperature goes down.

We just had a HUGE NE snowstorm in New England. The temperature was in the high 20's, low 30's. It was pretty windy. It was gusting in the 30's all day. Where I work, it was gusting over 60 for most of the day. I think it blew like this down in Provincetown, MA too.  Outdoor reset can not correct for these intermittent loads. That's my problem.



It's like NASCAR restricter plate racing. You have lots of power there. Y9ou just can't use it when you need it. Like  driving a truck and towing a trailer. You are driving on the flat. You come to a hill. You need to get into the gas. You can't because there's a block on the floor that limits how far you can push down the gas pedal. Part way up the hill, you are slowing down. Next thing you need to shift down but can't because you will slow down even more. If you could have got the revs and HP up, you could have made it up the hill.

Jean-David Beyer

Windy

"And as long as a proper heat loss is done and the boiler is sized to the

structure and not the installed radiation. Unless the planned water

temperature is used. Fine."



I did the heat loss, because the contractor did not. He just paced along the length and width of the house and counted his steps. I did the heat loss, and came up with half the loss he did. I have been through the winter of 2009-2010 and always had enough heat. I am not surprised because the smallest Ultra 3 boiler is 80,000 BTU/hr, and my house needs a little less than 40,000 at 0F and the design day temperature around here is 14F. Last January was pretty cold. This January we have had two storms. The first one dumped about 5 feet of snow around my house. The second one was less. The coldest day so far this winter was about 19F for a while one night. Predicted to going down to 13F tonight. Since the heating is hot water, not steam, I sized the baseboard upstairs towhat would fit along the outside wall, and calculated the temperatures needed to get the heat I wanted. With 14 feet of baseboard in each room, I could use about 135F water at 0F outside. I have no memory of it ever getting that cold, though it does go below 10F briefly (like once a year, and at night, not during the daytime. Had I needed hotter water than that, I would have used more baseboard, because I wanted condensation all the time.



" I just think the next step needs to be taken.

That the water temperature needs to be set UP when the room temperature

goes down. Like it does when the outside temperature goes down. "



That does not seem to have been necessary for me. Last year it was extremely windy so I diddled the reset curve for upstairs very slightly at the cold end of the curve. Made it hit 134F at about 8F instead of 0F. Recall design temperature is 14F around here. That was all I needed. The only setting up I do is when the room temperature goes down, the thermostat calls for heat.





"We just had a HUGE NE snowstorm in New England. The temperature was in

the high 20's, low 30's. It was pretty windy. It was gusting in the 30's

all day. Where I work, it was gusting over 60 for most of the day. I

think it blew like this down in Provincetown, MA too.  Outdoor reset can

not correct for these intermittent loads. That's my problem."



We had the temperature go down to about 20 on January 1 (I think it was), and gusts in the area were up to about 60 mph. I do not know if they were quite that high around here, but the drifting was considerable. Average snow depth was about 3 feet, but drifting had it up to 5 feet all around my house, and the second floor windows were covered in snow (could not see outside) because of drifting. I had no problems with heat at all.



Downstairs heating is radiant in slab, so it cannot follow gusts anyway, but on the other hand, if a cold draft did come in, the slab would cope with it anyway, even if the heat were off at the time. I have separate reset curves for upstairs and downstairs, and separate thermostats and circulators.