new tankless coil question

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  #1  
Old 01-06-13, 07:43 PM
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new tankless coil question

I just recently installed a new 117,000 btu output utica boiler that had a tankless coil.

I went with the unit that had the tank less coil because my boiler broke on a 0 degree day and that was all my supplier had in stock that was the correct size.

so now i have the boiler installed i have been listening to how often it runs and it seems to run for three minutes every 20 minutes with the high limit set at 180 and low limit set at 120 with the diff at 25.

my boiler has a max g.p.h. of 1.00. i ran some quick numbers and came up with 3.6 gallons of fuel oil a day. At 3.60 a gallon i come up with 12.96 a day. I don't know if my math is wrong but that is incredibly expensive if i'm right.

i had electric hot water before and my total electric bill was around 110 dollars a month. My electric hot water tank is shut off but still hooked up. It would just be a matter of disabling the low limit on aquastat and closing the valve going into the coil to switch back to electric hot water.

i was just looking for some advice on what would be a cheaper way to make hot water. I was also wondering if adding an indirect would be even cheaper than electric.

I live in upstate ny and generally have the heat on 7 months out of the year.

thanks for your help
travis
 

Last edited by NJT; 01-08-13 at 07:52 PM.
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  #2  
Old 01-07-13, 12:31 PM
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hi travis -

I can't help but the experts here will I'm sure. But I have a tankless coil also and it just doesn't sound right to me that your burner would kick on for domestic HW every 20 minutes?

Mine burner only runs for a short time (several minutes) also when there is no call for heat and the boiler temp falls below the low limit (adjusted with the diff), but it seems incredible that your boiler temp would drop that fast?

But I'm no expert to say the least.

Good luck!
 
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Old 01-07-13, 03:37 PM
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my boiler broke on a 0 degree day
Whattaya mean it 'broke'? You mean the cast iron cracked? Anything else can be repaired... so what was it exactly that broke, just curious.

my boiler has a max g.p.h. of 1.00
MAX of 1.00 might not be what it is set up to fire. What make/model is the new boiler?

My electric hot water tank is shut off but still hooked up. It would just be a matter of disabling the low limit on aquastat and closing the valve going into the coil
What did the installers do? Did they pipe the 'thankless coil' in series with the electric?

Be careful that closing valves doesn't seal off the coil in the boiler, you don't want pressure building in the coil...

advice on what would be a cheaper way to make hot water
You and I both know that the electric would be cheaper than $13 a day!

listening to how often it runs and it seems to run for three minutes every 20 minutes
Are you sure this isn't the thermostat calling for heat?

wondering if adding an indirect would be even cheaper than electric
It could be... pricey up front though, probably quite a bit over a grand to install...

Depends on your electric rates.
 
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Old 01-07-13, 06:55 PM
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yes the casting on the boiler broke and was leaking water into the burner box.

my boiler is a utica starfire 3 3100 with tankless coil.

i dont think the electric water heater is in series it seems to me that it is piped in seperately both the boiler and heater have there own cold water inlets and hot outlets which are not in series with each other.

i was running the idea through my head of piping it in series so that the cold water inlet to the electric water heater ran through the tank less coil so that even if the lo limit was disabled but there was heat in the boiler from a call from heat in the house it would help preheat the water going into the water heater. i didn't know if this sounded like a good idea so i figured i would ask around first.

As far as pressure building in the coil. being that the hotline out has a blow off valve if i were to just shut the valve off on the cold water going into the coil i shouldn't have to worry about pressure correct.

i found out today that my circulator pump is continuously running and that is why the boiler is cycling so often. i have been looking at my honeywell l1824 but have not been able to figure out why.

thanks for all your help so far any further help would be greatly appreciated

Travis
 

Last edited by NJT; 01-07-13 at 08:01 PM.
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Old 01-07-13, 08:24 PM
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i didn't know if this sounded like a good idea so i figured i would ask around first.
It's always sounded like a good idea to me, and though I've never researched it to find out for sure, I have heard some stories that certain manufacturers have a certain limit as to how hot the water going INTO their water heaters can be...

The water coming out of that coil could potentially be 180F which is way hotter than any water heater should ever be.

Bottom line... I don't know, hopefully someone who does and can provide the FACTS will chime in.

being that the hotline out has a blow off valve
It does? That's sorta unusual actually.

Are you sure that it's not a TEMPERING VALVE? These are increasingly required by local building codes.

I would say that as long as you don't valve off BOTH the inlet and outlet, your system should be able to absorb any pressure increase that the small volume of water in the coil will present.

I MIGHT be a little concerned about having a 'dead end' in the water system though. These so-called 'dead ends' are perfect places for creepies to breed. Google "Legionella" for some scary facts.

i found out today that my circulator pump is continuously running and that is why the boiler is cycling so often. i have been looking at my honeywell l1824 but have not been able to figure out why.
Something isn't wired right.

Do you have multiple zones on your system? i.e. electric zone valves?

If you have only one zone, or multiples with zone valves, the circulator should be wired to the C1 and C2 terminals in the L8124. Is it?

Are there any wires on the ZR and ZC terminals?
 
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Old 01-07-13, 08:26 PM
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By the way, in the interest of 'readability', may I ask that you add some 'white space' to your message? I've edited your last one to illustrate. Run on paragraphs are hard to read. You're probably on a smart phone I bet!?
 
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Old 01-08-13, 06:20 PM
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aquastat picture

Sorry about my previous posts i agree they are hard to read.

yes my house is all on one zone. The circulator is wired to c1 and c2. there are no wires on zr or zc.

The blow off valve for the dhw came with the boiler. I had to buy and install a tempering valve seperately.

thanks for your help
Travis
 
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Old 01-08-13, 08:00 PM
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Did you do the install yourself?

The blow off valve for the dhw came with the boiler.
I think you may be talking about the pressure relief valve for the BOILER, and if so, it won't have anything to do with the tankless coil hookup.

Is there a metal tag on that valve? Does it say 30 PSI ?

At the upper left of that pic you posted is a gauge visible.

Are my eyes playing tricks on me? or is that pressure gauge reading ZERO PSI?

If you disconnect the thermostat from the T T terminals in the aquastat, does the pump still run?
 
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Old 01-10-13, 05:55 PM
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Cool

Yes i did the install with the help of my brother who used to do hvac.

Here is a picture of the pressure releif valve on the dhw out line. It has a tag but i could not find a pressure rating.

The pressure was at 10 psi when the boiler was 120 degrees. a little low so i added a little water. I have been still been getting random bits of air out of the system. My brother still needs to adjust the auto filler. I have been filling the system manually for now.

The gauge is hard to read even in person. They could have made the scale a little bigger.

Disregard the post about the pump running. When i actually checked out the multimeter it was not running. i thought i could here it running but i was wrong. i never thought i could get heat transfer all the way up to the second floor without a pump running. What i did find is that i think i need a flow check valve in the system. If i let the boiler come up to temp then close the valves on the supply and return after it shuts off. The boiler will hold 25 degrees for over two hours. With them open only it only lasts for for fifteen minutes.

I am including a pic of what i thought were check valves on the return line. i'm wondering if you can tell me what they are. and where i need to have check valves in the system.

thanks for all of your help so far nj trooper you have been great.
travis

p.s. i've got the spacing down but the quotes are above my skill level
 
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Old 01-10-13, 08:44 PM
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i could not find a pressure rating.
Not on the round metal tag on top?

Please double check those relief valves... make sure that the 30 PSI one is on the boiler and the one on the DHW is probably higher... quite a bit higher.

You should have pipes down to within 6" of the floor on those relief valves.

Technically they should both be mounted vertically as the one on the boiler is.

The gauge is hard to read even in person. They could have made the scale a little bigger.
With that quote, you just told me you are over 45! Yeah, I was there once... long ago!

i never thought i could get heat transfer all the way up to the second floor without a pump running. What i did find is that i think i need a flow check valve in the system.
Yes... didja know that years ago they didn't even have pumps on the systems and relied only on gravity and thermosiphon to move the heat around the home? You are learning how powerful that process can be!

thought were check valves on the return line. I'm wondering if you can tell me what they are. and where i need to have check valves in the system.
Those are 'balancing valves' which are basically a 'butterfly valve' like you would see in a carburetor. They are 1/4 turn jobs, when the screw slot is parallel with the run of pipe, they are fully open. If the screw slot is perpendicular to the run, they are closed. I presume that they were already there with the old system? I mean, if you put them in, you would have known what they were... one would assume anyway!

If you can draw some sort of system diagram I might be able to tell you where the flow check valves need to go.

If I wuz you, I would remove the handles from those 'future use' ball valves just so they don't accidentally get bumped. Unless you like hot boiler water bidet and shower! Hang the handles on a nail near the boiler, or sweat in capped pipe stubs and leave the handles in place.

i've got the spacing down but the quotes are above my skill level
Yes, you sure do! Perfect!

If you see that 'icon' above the message box that looks like a 'callout' box, clicking that will insert the open and close quote 'tags' into your message. Any text that is placed between those tags will
appear inside a quote box.
 
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