new tankless coil question

travis9791

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

STEVEusaPA

travis..

Are you saying your boiler is firing 3 minutes, every 20 minutes, just to keep the boiler hot, for DHW?

Whats the boiler temp (on the gauge) when the boiler fires (assuming it's not calling for heat).  Doesnt sound right.  Are you sure theres no faucets dripping anywhere in the house?

In my opinion, the cheaper way would be with in indirect, but first determine why the boiler is running so much.  Clock the water meter when nothing is 'on' to see if some cold water is running thru the coil.  Also make sure your triple aquastat is working properly.

Icesailor has a pretty good system for hooking up a boiler to an existing water heater.  If he doesnt respond Ill try to look up the thread.

travis9791

steve

 so i have just discovered why my boiler is firing so often. It is because my circulator pump is continuously running. so far i have been unable to find out why. I have been looking at my aquastat which is a honeywell l8124a to see if i can find out why but the scematic that came with it is rather confusing to me. From what i see all the wires are where they should be. the only wires i touched installing the aquastat where the power wires coming in. I would appreciate any insight you may have on this problem. Also i would definately be interested in hearing the setup with the electric water heater



thanks

Travis

JStar

Heat

Maybe the pump is not actually moving any water.

Paul48

OK

Take the cover off that aquastat and take a good picture, so we can get a look inside.

travis9791

picture

here is a picture of my aquastat.

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



thanks

Travis

Paul48

Hmmm

Got a multimeter?

travis9791

mutimeter

Yes i have a multimeter

Paul48

?

Check L1 & L2, see if the polarity is flipped?

travis9791

i was wrong

so i had to go by a new multimeter today because i could not find my old one.  After confirming that the polarity was correct. I decided to test power to the pump because it was my ear that was telling me that the pump was running before.  well apparently my ear was lying to me because the pump only turned on when the thermostat was calling for heat. just like it should be.



 So now i don't know what to think. my radiators seem warm all the time.  My  house thermostat is set at 65 but the temp is always around 73 or 74. whereas before it would only get to around 68,  and my boiler is kicking on every fifteen to twenty minutes for three minutes at a time. I thought for sure it was  the circulator pump running all the time that was causing this. I have never had a tankless coil before so i don't5 know if this is normal but it doesn't sound right to me.  The high on my thermostat is 190 my low is 120 and the diff is 25.

Paul48

?

Got a flow check above that boiler?

travis9791

were getting somewhere now

So i think that you hit the nail right on the head. I must be getting flow from gravity and migration of heat. To confirm that this is the problem after the boiler warmed up to 145 and shut down i closed the valves on the supply and return and also closed off the domestic water outlet.  The boiler has been off for an hour now and i have only lost five degrees.  Whereas before i was losing 25 degrees in 15 minutes. I thought i had  flow check lines on the return lines to the boiler they were ther in the previous plumbing and i left them in when we replumbed the new boiler. i am posting some pics in hopes you can tell me what they are.



 I was also wondering where these valves should be in the system.



one other question i had was if i would benefit of putting a thermal trap on the hot water outlet for dhw.  I noticed now that it is in the diagram for the boiler.  we just piped straight up to the hot water.

Paul48

They

appear to be swing checks, and I have no idea why they're there. They won't stop gravity circulation, as you already know.Back up, and take some pictures so we can see the near boiler piping. We can blow the pics up if we need to.

travis9791

more pics

Here are  more pictures. I know i still need to install a tempering valve; and also a flow controller going into the coil. They will be going in this weekend. By the time we realized we didn't have them last weekend the supply house was closed. The manifolds that you see in the pictures are for baseboard heaters i plan on adding to the system later.



 i was wondering what a swing check is. The t that you see them on are where the two return lines come together and go into the boiler.





Thanks

Travis

travis9791

more pics

more pics

Paul48

FloChek

Put this where you turn 90 degrees coming out of the top of the boiler. The extra hole gets plugged.It has some weight and will stop gravity flow, but will easily open with flow from the circ.  http://www.taco-hvac.com/en/products/Flo-Chek/products.html?current_category=183

A swing check is just a hinged check valve.Curious....I only see 1 supply connection, but you appear to have 2 return connections?

travis9791

installed check valve today.

So i got my new check valve in today. It seems to be working well so far. I will be doing the tempering valve tomorrow.  I have two things left that are on the diagram that came with the boiler that i have not done. One is piping the dhw outline so that it has a thermal trap, and the other is installing a adjustable flow restrictor on the cold water inlet to the dhw coil. I was wondering  what your opinion was on weather i need these two things. My brother seems to think i don't need either,  but i would like a second opinion.

 If it would be beneficial i would spend the time and do it right.



here are some pictures of my new check valve installed. It may not be the prettiest solder job but i had no leaks.



Also here is another picture of my pipes the the top t that you see is the supply and the bottom t is the return 

Paul48

If

you're happy with the hot water, don't bother with the restrictor.If you're doing the thermostatic mixing valve, do the thermal trap.It's just forming a "U" in the pipe.

icesailor

Flow restrictor:

If yo bought a boiler that is smaller than the old one, you won't get good hot water production without the flow restricter. If you have a water heater connected, connect the water heater as a storage tank. If it is close by, you do not need to change the piping to and from the water heater. Just the coil to and from the heater.

travis9791

?

Icesailor



Are you talking about having the water go through the water heater first and then into the coil to collect heat from the basement.  My water allready has heat from the basement because i have two 200 gallon tanks in my basement. These tanks are filled from the well. Then there is another pump that feeds the house from these tanks. So my water is allready warmed to basement temperature.

 I did think about piping in an extra loop to the hot water heater that would take water in from the domestic coil.  So if i was using the electric heater and the boiler was warm the water would get preheated from the boiler before going into the hot water heater. this may be a cheaper setup early or late heating season. I am thinking electric will be the cheapest way of making hot water in the non heating season but i have not crunched the numbers yet. Any advice you may have will be greatly appreciated.



Travis

travis9791

question on thermal trap

Paul

The diagram for my boiler shows the bottom of the thermal trap being 8 to 12 inches below the outlet of the coil.. I was wondering if i put the thermal trap above the outlet if it would still be doing anything. It would be considerable more work if i had to  pipe it in below but if that is what needs to be done to get the job done that is what i will do.



Also in the diagram for my tempering valve it shows an optional check valve that is part of the tempering valve. If i were to put the check valve in the tempering valve would this eliminate the need for a thermal trap.



Thanks

Travis

SWEI

thermal trap

you can go up as long as you drop down.



Thermal traps are specified even for mixing valves with built-in checks (in case a check fails.)  There are ways around it, but traps are simpler and cost less.

Paul48

I'm

not looking at those directions, but, there's no way any optional check valve could be positioned to take the place of the thermal trap. The hot water has to be able to flow into the hot of the mixing valve under normal operation. Just not because of thermal convection.