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TKjr2 heat issues
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MR_P_BODY
Member Posts: 40
I am running a TKjr2 on a closed system with 3 loops of 1/2" pex in a 5" thick slap of concrete each run is about 250 ft long the TK unit is new to replace a old TKjr... my issue is that I can fire it up but after about 2.5 to 3 hours of run time
the unit shuts down and doesnt restart on its own.. if I flip the power off then back on it fires up again.. NEW GUY HERE
I have no codes on my read out
thanks all
the unit shuts down and doesnt restart on its own.. if I flip the power off then back on it fires up again.. NEW GUY HERE
I have no codes on my read out
thanks all
0
Comments
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Have you cleaned the Takagi filter? You might have loosened up some debris in the system when you changed it out and it collected in the filter. The reduced flow will prevent it from firing.
Also, is it piped primary-secondary? These on-demand water heaters have a high pressure drop through their heat exchangers and need a dedicated pump.8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab
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I took that small filter out but put in a remote filter(much larger).. I am running between .5 and .8 on the flow.. never seen it above .8 or so0
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Forgot to say I have Taco 1/4 hp pump on this0
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I believe the flow switch needs at least .75 gpm before it will allow the burner to come on.
What model Taco pump do you have? Can you post pictures of the piping?8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
I think I found the issue.. looks like 2 of the loops may have blockage in them.. only 1 loop is flowing so I need to open the
other 2 loops and see if I can blow them clean.. I'll start on that
tomorrow... thanks for the help.. I'll let you know0 -
I am assuming that if 2 loops are plugged up my flow would be way down.. I have no idea why they would be plugged up.. hope I can get them cleaned out and pick up flow0
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New system are often air bound.
Can you tell us the Taco pump model number? It's on the wiring cover.8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
The pump is a Taco 0011-f40
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Your overall issue is that you have a tankless water that isn’t designed for the application you have along with the piping being all wrong.
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I was thinking their could be air in the 2 loops but figured it should bleed out but not yet... this system has a manifold forNew system are often air bound.
Can you tell us the Taco pump model number? It's on the wiring cover.
intake water and outlet water but I guess if the water isnt pushed
out it would still have air in it and just sit there.. when I flushed the system last year I was pretty sure it was full but I guess I could have screwed up0 -
At 1.5 gpm (3 loops @ .5 gpm per loop), the pressure drop through the Takagi is 7'. Add another 3' of head through the tubing and your total is 10' of head at 1.5 gpm.
The Taco 0011 is way too big. Replace it with a 008 once you get the air out.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
Is there a easy way to get the air out of the system.. any tricks0
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You want to do primary secondary with a 008 and take the filter out you will be to 4 gallon per minute, I run my parents snowmelt system with the tk 30
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Also that piping has to be 1 inch minimum1
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Well it was running fine for 11 years before the old Taco pump died.. now I'm trying to get all the air out of the system and its being a PITA0
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Add two ball valves to isolate and flush through the hose bibbs.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
Thanks for the drawing.. I will have to add 1 more valve and a outlet1
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Well I put in another drain and ball valve and I did get the flow up some to 1.1 GPM but just for a short time then it drops back to .5 GPM.. I still believe I have air in the system.. anyone have any ideas how to get the air out of this system.. would be a BIG help
thanks guys0 -
Did you power purge using household pressure like this drawing shows? You could then reverse the hoses and purge the boiler and circulator.Add two ball valves to isolate and flush through the hose bibbs.
The circulator installed like that is not helping and will lead to premature failure, The motor should be horizontal. If the circ is oversized for the piping and system as it appears to be, It will tend to pull air out of solution on the inlet. I'll bet a bubble is forming in the pocket created by the incorrectly installed circ."If you can't explain it simply, you don't understand it well enough"
Albert Einstein0 -
I was told that the pump SHOULD be facing down but later was told its wrong.. I changed it so the motor is facing UP.. I havent uses house water pressure to purge yet.. I have a separate pump with antifreeze(RV type) that is filled and use that as a pressure source..Right now I have a inlet and valve for both inlet and outlet as in your drawing.. I have been running 40 psi on the system IF my gauge is correct and I doubt that it is0
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Also do you purge 1 zone at a time or all of then together.. I have
been trying both ways0 -
The pump must be horizontal, not vertically up or down.
Your gonna need to pipe the system primary/secondary with 1" pipe all the way if you hope to see it have any functionality.
A tanklees water heater is still the wrong appliance.Bob Boan
You can choose to do what you want, but you cannot choose the consequences.3 -
One loop at a time if you can.
The way this thing is put together, the circulator is probably pulling air out of solution on it's own creating it's own perpetual air bubble.
Your setup is violating at least a half dozen rules of hydronic design."If you can't explain it simply, you don't understand it well enough"
Albert Einstein3 -
Re-plumbing with 1" isnt going to happen.. this is a existing system.. whats wrong with a tankless system.. I was told it would
be fine by multable people including a couple of pro builders0 -
A tankless is not designed, controlled or approved for space heating. Its heat exchanger has way too much resistance to flow (head) for hydronic circulators that produce about 5 psi pressure differential. It’s designed for 60 psi coming in and an open faucet going out. It’s also looking for a 77* delta T, not the typical 10-12* of a radiant floor.
Why would you go to a builder to get hydronic advice? If he knew how to do it, he would be trained, well experienced and have a license to do it. If I wanted expert advice or help with body work on my Ram dually, I wouldn’t go to a house painter.
The men giving you advice on here are hydronic experts with decades of experience designing and installing radiant systems. Please follow it if you want your system to work.
Think about it: if a tankless water heater could replace a boiler, there would be no need to make boilers.Bob Boan
You can choose to do what you want, but you cannot choose the consequences.
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Tankless water heaters are not designed to be used in heating systems. They have high flow resistance and are not designed for the constant workload of space heating.
Do they "work"? , usually....
They are very popular is some regions and do save some money upfront as they are cheap (and cheaply made).
I have never met a "pro builder" that knew anything about heating systems. I know a lot of builders....
You have a handful of design issues which are making it difficult to remove air. It is not a purging technique issue at all.
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein2 -
When I said builder I was referring to a hydronics person and I
took there advise... so what kind of heating unit is adviced for my type of system.. I can change that part but the water lines are there and they arent changing0 -
My suggestion would be a condensing boiler, appropriately sized circ(s) and primary/secondary piping.
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein0 -
The Takagi will fall apart soon anyway, and you can replace it with a real boiler when that day comes. Until then, the 3/4" pipe is just fine and so is the 011, aside from it being vertical. Taco does say it's fine to have them vertical if over 20 psi, but I still wouldn't risk it. You need to purge the system using an external pump, through a couple valves like Alan drew for you or personally I prefer the "purge valves" made by Webstone. Three washing machine hoses, a pump, and a bucket. Get that air out of there and let it run until it dies0
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I do have the valves your referring to,, just got a couple the other day.. I need to get a bucket to dump into and draw from it.. right now I have been dumping out the door onto the ground.. I need to be able to dump into a bucket and draw straight fluid for the return0
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It's not too big, at all. The pressure drop through these Takagi units is ridiculous- a huge circ is required to have proper flow when not piped P/S. I too have used them quite a few times as well as worked on many many systems which have them piped direct, your regular 15-58 or 007 variety of circ will not flow any amount of fluid0
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What are you guys talking about when you say primary/secondary piping0
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@GroundUp , the 011 is waaay big for the application, not to mention, it's off the curve by miles. It is simply not designed for this application which is part of the problem.At 1.5 gpm (3 loops @ .5 gpm per loop), the pressure drop through the Takagi is 7'. Add another 3' of head through the tubing and your total is 10' of head at 1.5 gpm.
The Taco 0011 is way too big. Replace it with a 008 once you get the air out.
@MR_P_BODY , With primary/secondary, you have to independent loops. The boiler gets the flow it needs and the radiant get what it needs. Both circulators could be much smaller and the system would be happy (and air free).
https://www.pmmag.com/articles/85102-primary-proportions-john-siegenthaler"If you can't explain it simply, you don't understand it well enough"
Albert Einstein
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If I Google hydronics all I come up with is hydroponics..trying to look it up and get more0
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It should look like this:
The closely spaced Tees allow flow from both circuits to mix without the flow rate from either circuit interfering with the other.
The heat exchanger in the heater has an extremely high head, much higher than the floor. Therefore, the heater will need a “high head” circulator. The floor will need a standard Taco 007 or Grundfos ups15-58.
Look up “hydraulic separation”. P/S piping is one means of achieving it.Bob Boan
You can choose to do what you want, but you cannot choose the consequences.2 -
I found it.. I put in too much data before
thanks0 -
What I see from what you show and what I have is that you show 2 circ pumps(1 before and 1 after the heating unit).. is that correctIronman said:It should look like this:
The closely spaced Tees allow flow from both circuits to mix without the flow rate from either circuit interfering with the other.
The heat exchanger in the heater has an extremely high head, much higher than the floor. Therefore, the heater will need a “high head” circulator. The floor will need a standard Taco 007 or Grundfos ups15-58.
Look up “hydraulic separation”. P/S piping is one means of achieving it.
Thanks0
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