Can this install be salvaged?
Just had my hydronic system redone with an updated boiler (nti tx 200). The fella who did the work did not plumb a proper primary/secondary system. I knew how I wanted this system done but being so busy with work I left him up to it( and I trusted he would install accordingly since I have seen plenty of his work elsewhere). Anyways, I came home to this install.
I painted the loops with colors accordingly so you can see where they supply and return.
So basically piping comes straight out of the boiler into a single loop with a circulator(CH). All the zones ( 5 infloor and a fan coil) as well as the DHW with its own circulator to indirect tank (DHW) are piped off of this single loop. I guess you can sort of call it p/s but the boiler is not hydraulically decoupled from the system.
It’s not winter yet so I still do not know how the system is going to work with heavier demand from all zones but here is what I have witnessed so far:
The system sort of works
Call for DHW : yes it is satisfying the demand and keeping hot water in the tank but, the circulator is flowing hot through the whole main loop and even to the fan coil and some of the other zones.
Call for central heat from any zone: CH circulator is pushing hot backwards through some of the individual zones that are not running. I think this due to the pressure difference from the return being after the pump, and the supply before the pump.
Now the worst issue I think is when the fan coil zone circulator is running , it will not flow unless the CH pump is on its low setting-obviously the fan coil circulator cannot overcome the pressure difference at the return. So now with the CH pump on its low setting I don’t think it will provide enough total flow when multiple zones are running.
I am going to call the guy back to make some changes. Without totally ripping this piping out, any ideas on how I can modify the piping?
Some of my ideas: A check valve in each zone as well as after the DHW pump and CH pump?
Diff pressure regulator between boiler supply and return?
Comments
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Are there flow checks in the circulators? Each zone needs to have a flow check if you are zoning by ciruclator.
Is there a boiler circulator in the boiler?
It can work if you are careful with your math and make sure all possible combinations maintain the minimum flow through the boiler and that the flow in the boiler loop isn't enough to open the flow checks in the zones. This setup might work better with zone valves.
That air scoop isn't great, much better to use a microbubble air separator.
If the DHW isn't piped separately to the boiler then the "ch" circulator is actually a boiler circulator and needs to be set up to run whenever there is any call. There is usually a menu setting or terminal for that.
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There are no flow checks in the system at all. The boiler does not have its own circulator. The dhw is piped into the main CH loop with its own large circulator so it is essentially acting like a zone except it has priority. Dhw works at the moment , but when it’s running it’s putting heat through other zones as well
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You need to get the flow check that goes in the zone circulators and add them. The DHW is just another zone for the purposes of this design(that has priority over the other zones).
The circulator labeled "dh" is the boiler circulator in this case since it does not have an internal circulator. It would be better if the zones connected to the boiler loop with closely spaced tees but it will probably work the way it is. If you get ghost flow even with IFCs in the circulators you will need to change the zone connections to closely spaced tees.
Is all the tubing that goes in the floor to emitters that can take high temp water like baseboard or panel radiators or a fancoil? None of it is in floor/wall radiant?
The "ch" circulator is in a loop from the boiler outlet to inlet, correct, it will flow even with all the zones closed off? It is hard to follow in the picture.
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Three of the 5 zones are the red pex in concrete, two of the zones are not the red pex type they are under upper floor tile laying on top of reflective insulation. So I have the boiler temp at 120deg for all zones. The fan coil definitely works better at 140 or 160 but I would think that is to hot for in floor runs.
yes the CH circulation pump is in a direct loop with the boiler. But only runs with a CH call.
when the dhw is running it is still flowing through the boiler as it holds 160 deg . no issue with overshooting that ive noticed0 -
Is the Red PEX the type with an oxygen barrier?
If there is no oxygen barrier, then you must have all non ferris metal fittings… pumps… and other accoutrements. That is because any iron pumps, steel pipes or fittings will rust and fill up the system with mud over time. So if you don't have O² barrier PEX, then you have a lot of work to do to get this right.
Check writing on the PEX tubing to see if it has that all important O² barrier.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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I will have to check the pex . The only iron part in the system would be the air scrubber and non conduction couplers at the water tank and boiler connections. Everything else that the fluid touches is brass copper or stainless I believe. Also I use a 60/40 glycol/water mixture so there is some corrosion inhibiting ability.
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Pretty sure those grundfos circulators for the boiler pump and dhw are cast iron. do you need glycol? it changes a lot of things in a way that makes things worse.
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You can’t run a fan coil, radiant floor and indirect with the same supply water temperature (SWT). The floor requires a much lower SWT than the fan coil - like 100* maximum if it’s a slab vs. 140-160* for the fan coil. There needs to be some form of mixing system for the lower SWT.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.
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Thanks everyone for all the reply’s .
Your right those grundfos pumps are iron. We have winter temps down to -40c here so need to have glycol.
as far as a mixing system goes I’m not sure how to go about that without tearing this down and stating from scratch but it’s been working at 120 deg temps maybe not so efficiently but it works.0 -
Please...do us & yourself a big favor: cut out the Taco Air scoop and install a Taco 4900 series Air Seperator, Spirovent or Caleffi please....Mad Dog
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What was there before? I see five bronze circulators telling me the tubing is all non barrier tubing and this makes me think there was a water heater acting as a boiler prior to this install. I'm just curious.
Miss Hall's School service mechanic, greenhouse manager,teacher and dog walker0 -
I too am curious what was there before. Will this work? Maybe. Is it right? No. Hydraulic separation is a must, and no amount of check valves will accomplish that without changing up the piping. Dual temp is necessary to maximize efficiency, however the fan coil may be okay with the low temp water if sized adequately to meet demand with low temp. The indirect will take priority and have its own water temp, so that part is irrelevant if the settings are dialed in properly. The air scoop is not ideal, but is not as big of a problem as many make it out to be UNLESS the tubing is non-barrier, in which case, this gets even more hairy and would require a heat exchanger or to switch everything to non-ferrous. I'm also a bit concerned with the size of the boiler- 200k for what appears to be less than half that on the load side based on pipe and circ sizes is a very poor fit.
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Checked the pex tubing it is O2 barrier.
Grallert, this is correct, Originally the system in this house was a Lennox all in one furnace /water heater unit which they also used to handle the infloor heat. Apparently it was a nightmare. This is way before I purchased the house. All that’s left of that is the fancoil hvac unit.That was replaced with nti ti200 in 2012 which lasted surprisingly until 2021. I then installed a Weil McLain wmb155 lasted till August 2024. I just replaced this with a tx200 along with all the piping this July. Cost was a big factor here as I paid 1000$ for this tx200 which was basically new from a failed beverage business.
As far as sizing the sizing goes yes the 200 may be a little large but the previous 155 struggled in the dead of winter when all zones were calling.
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I suspect the struggle had to do with the near boiler piping rather than the size of the boiler but a heat loss of the building and checking the emitter sizes would be needed to figure out where the problem is, especially if it wasn't making 180 f or so water for the fancoil. A good heat loss would tell you if the fancoil can work with low temp water. If it can't you would have to make a mixed supply for the radiant or possible replace the fancoil with a gas furnace.
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Didn't the installer simply do the basic swap? If it worked before, it should work now. I feel bad for homeowners who don't know what is happening and not happening. We try to be very specific as to what materials are staying in operation, which materials are getting updated, and what we are doing to improve things.
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no, actually the piping was completely redone reusing existing circulators etc. , boiler and water tank relocated for better maintenance access. The old system had a clear p/s loops. It worked, but it was very ugly and hard to work on. I expected this guy to install properly after seeing some of his other work so I let him be.
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with the O² barrier PEX question answered, The next step is to look at the manufacturers instruction manual for the piping diagram the most closely matches your system. Let me take some time to find your boiler. Can you post the brand name of the boiler and the model number. You can usually find a sticker that has the information.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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I'm not sure if this is your exact model number, but It should be close. Your first step might be to remove all the near boiler piping. That is what I would do. And it would cost you dearly as a professional pricing this job for you. You can save big bucks if you are a DIY that is confident with soldering or renting a ProPress tool. OR if you did not pay for the job in full, then call the contractor to make it right!
This is the first step. You need to make sure the safety features are installed according the the manufacturer's specifications. Here is the first step for proper piping and relief valve location, after hanging the boiler on the wall
if you are sure that this piping and the existing piping are the same, then you can go to the next step
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Yes that’s the right boiler . Piping as shown is correct to that diagram.
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Ive made the decision to redo the piping . I will pipe according to the manufacturer recommendations and be done.
What would be the recommended way to install a mixing valve to bring temps down for the three In floor concrete zones. ?0 -
The only time you need to mix down the floor heat is if you have any finish on there that doesn't like heat (ie hardwood). If it is all concrete, you can leave it as is. You'll get a bit more striping but I don't think it will matter much.
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False. Extremely false. Do what you want in your own home, but please don't try to tell people things like this when they are looking for the proper way to do things.
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@wkotelko there are many ways to skin this proverbial cat. A regular old 3 way thermostatic mixing valve (something for hydronic with less flow restriction than the typical DHW valves like a Taco 5000 series, I prefer the Honeywell/Resideo AM series) with the circs drawing from the mixed port is the cheapest and easiest route. Injection mixing is an option with a 0-10V circ and proper controls. You can get fancy with something like a Tekmar or Taco iSeries motorized mixer which can adjust water temp based on outdoor temp. The last is going to be the most comfortable and efficient, but you're unlikely to notice the difference unless you're really looking for it compared to option A with the basic 3 way.
This is one I built awhile back that may help illustrate the idea of the thermostatic 3 way. Upper circ is high temp while the lower 2 are low temp. That is a Honeywell AMX mixing valve which allows a straight through design unlike most (Caleffi 520 also has a straight through but it's more bulky in my opinion)
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@GroundUp Those fancy all in one thermostatic manifolds with circulator are real cool looking. Very expensive though . I think the best way for me to go is to install a standard mixing valve on the three low temp zones.
Im going to draw my plan up in the next few days and I’ll post it on here0 -
I've actually tried it with 150F water. A typical slab has enough heat capacity that doesn't matter what temperature water you dump into it, the overall temp of the slab will not change much in any reasonable timeframe. The hotter supply feed will mean shorter runtimes for the zone. You'll also get striping where the hot water gets into the slab, it might get too toasty there for bare feet.
Snow melt is the same. No need to mix the water down.
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The next step is to match a diagram from the manual to your system. Since there is no diagram for a multi temperature system, and you have some low temperature zones, and high temperature zone for the fan coil, and a DHW tank, I selected this diagram as the one that most closely matches your system.
I will doctor it up to match your components by removing the zone valves and adding the necessary mixing valves. this is the lowest cost way to accomplish what you need.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Since you are zoning with Circulator pumps I will redesign this diagram to match your system.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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This is an alternate that uses one less circulator.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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the zone and the dhw circulators need to have the flow checks installed in them
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This will work with the equipment I have . I would need to purchase another circulator to build your first design. I have the check valves as well for all the zones.
I do have a toco 5000 series mixing valve at home. @GroundUp mentioned that this may not be the right fit for a hydronic system . What are your thoughts should I get a different one with a better flow characteristic or can I get away with it. Also I have been reading that I should look into a diverter style mixing valve to prevent cavitation if the hot side closes off completely .
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Why do so many seem to recommend thermostatic mixing valves? I despise them. If the boiler is operating on outdoor reset all you need is a proportional mixing setup to mix in a portion of the water that is returning from the zone. I have done it on many systems. For consistent operation each zone needs its own close tees and bypass valve so that there are no pressure differences that could affect flows depending on how many other circs are running. Doing it proportionally will allow you to still have an outdoor reset temperature instead of a flat temp. Will try to post a drawing.
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I don't see why outdoor reset wouldn't work. Wouldn't the mixing valve compensate with varying hot inlet temp to keep desired temp in the zones
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If it is a basic thermostatic valve it puts out a flat temperature. The only exception would be if the reset on the boiler puts out a lower temperature than the valve is set for, then of course, the temp to the zone would be lower. A proportional mixing setup gives less flow restriction, less cost, and a temp that will vary with the system temp. Will try a pic of an 20yr old system we did (since I don't have a more recent system pic on my tablet). The long stack of circs on the left is the floor heat zones. Notice the zones at the bottom have what I call a crossover between supply and return
which is a simple proportional setup. Those zones are for the in concrete heat while the others are stapleup or aluminum plates.
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To your point about using a mix valve or a diverter valve. This is a video that explains that difference.
However I did not include the check valve in the piping between the primary and secondary because the design is not exactly the same as the the one in the video. So the Mixing valve you have should work just fine, as long as it is within the temperature range you need.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Well it took a while to get all the parts lined up and a full 3 days to complete the piping and wiring but I got it done. I splurged on some goodies like a hydraulic separator and manifolds for the infloor concrete zones. I was able to incorporate the mixing valve for the concrete zones keeping the temps down . I’m happy to say it is working well . Lots of condensate dripping into the drain now and no short cycling of the boiler.
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