A question best posed to your Hvac contractor, no?

Nope. A question best posed to a few different people with different bits of knowledge about it.

After a week you have reached a balance point between the heat going into the room and the heat lost by the room to the surroundings; you either don't have enough heat going into the room or there is too much heat being lost by insufficient insulation, etc. Probably a good question for your HVAC contractor.

This is a newly built house? Was a load calc done for this room?

If you'd rather speak to anyone other than your contractors, even people with no technical knowledge or experience, that suggests you have no confidence in your contractors and you weren't successful with your hiring choices. Hire a new one.

You either found the capacity of the system or the heating source isn't working properly has a problem.

Capacity : the limit the system (what ever it is) can achieve. A thermostat is a switch, just because you punch a number into it does not mean by any stretch of the imagination that the system can reach that temperature. (magical words: design... the invisible thing that if not paid for will result in disappointment.)

Backwards analogy: I want to put 50 gallons of gas in my gas tank, but every time I try 20 gallons spill on the ground. ---- capacity limit. (I know how stupid this sounds, but after reading that there is no way you don't understand what 'CAPACITY' means and I don't want to repeat myself. If you're offended... welcome to the internet.)

I am no expert in radiant floor heating. So forgive me if I ask questions. Does the thermostat only set the water temperature and not the temperature of the ambient air in the room? Is the 104 degree the maximum setting on the thermostat?

My understanding:

The circulating water temp is between 140 and 170°f.

For thermostats, in our case it depends on the room and the purpose of the system. Some have both a floor temp and ambient temp sensor. For example, in summer a bathroom can have a floor temp of 72°f for some barefoot comfort and ignore ambient while in winter it will attempt to achieve both a comfortably warm ambient (70° for instance) and floor (90° in winter).

Thermostat in the room creates a call for heat, opens valve, turns on circulation pump.

When temp is reached in room the valve closes, circulation pump turns off. If temp is not reached (capacity problem) the boiler runs and runs and so does the circulation pump.

Room thermostat is merely an elaborate switch to call for heat.

@Elmer J Fudd, I wish life were as simple as 'hire a new one'. I'd rather make myself as knowledgable as possible so that I can understand what are and are not issues and talk intelligently to our HVAC contractor.

Where is the thermostat? If it is not on the floor (or doesn't have a sensor on the floor), then there's no way it can know the floor temperature. HOWEVER, if your circulating water temperature is over 100F, then you're losing a lot of heat somewhere. How much insulation is there under the floor?

Thermostat is in the mechanical room. It has a floor sensor and ambient air sensors in the conservatory.

Floor is spancrete w/ about 10" of closed cell foam on the underside (w/ sauna below that). IIRC they did 4" rigid foam on top of the spancrete, attached the hydronic tubes to that, poured 3-4" of gyp to encase the tubes with brick on top of that.

Our radiant system is much older than yours so it is hard for me to understand the set point of 104.

For instance our boiler goes on at 160 F and off at 180 F. So that is the boiler circulating temp.

There is a mixing valve that mixes return floor water with heated boiler water and is set to 130 F. It isn't precise so probably varies between 120 F-140 F depending on how hot both feeds are. This is what is sent to the floors.

There is a thermostat that controls the valves that open to allow this water to circulate to the floors. They are generally set on the wall above the manifold where the water tubes enter the floors. They keep the room at waterever temperature we set it to.

My guess is if your 104 F is equivalent to our 130 F then the temp is too low to properly heat the room. Or if you are unhappy with the room temp then you needs to set the ambient temp for what you want the room to be and ignore your floor sensor. We don't have a floor sensor so I'm not familiar with that.

Radiant in floor is probably not a good heating system for a conservatory. The floor will be very comfortable but you're going to need another heat source to keep the room temperature at a comfortable level.

There's a saying that a person who acts as their own lawyer for a legal matter or in court has a fool for a client. That's apples and oranges with the situation you describe but the sentiment fits.

It sounds like you don't have confidence in your HVAC contractor and maybe for good reason. An expert doesn't need help from their client or customer to do their work, answer questions, or resolve problems. Hire an expert and let them do their work.

Good luck.

I believe the person is talking about a newly built home. If out of the box the function isn't what was spec'd and desired, there's at least one contractor and maybe more (if HVAC subbed out to the General) accountable. Acting like a self-deputized know it all won't help.

Thermostat is in the mechanical room. It has a floor sensor and ambient air sensors in the conservatory.

Thermostat in mechanical room is for? Is it used as a control center to read or set floor sensors / ambient air sensors?

I think this system would be overly complicated to control because most likely the floor sensors and ambient air sensors relay back to the thermostat in the mechanical room? Which likely means that thermostat is a 'control hub' so to speak than an actual thermostat. Of which we don't know... probably because you don't know either.

So depending on how the system is designed it might be control related issue like if those floor / ambient air sensors can each be programmed to a certain temp / one errant setting may pose issues which is another reason trying to get pointers in a forum board for a *likely* complicated system this probably is : futility at best.

This is why you do the hard work up front before such a system is installed to make sure you know *exactly* what you are buying.

Another issue could also be short cycling so the list goes on and on as to potential problems. Design of the system plays a very important role.

Modern radiant in-floor is being used to heat homes, shops and farm buildings in the Dakotas and Minnesota, so it definitely has the capacity to heat a large room if its properly designed. However, I don't know how well designed the OP's system is.

I'm not an expert on in-floor radiant heat, but 104-125 degrees for water circulating through the floor does not seem unusual for this type of system. You would not enjoy having your feet in direct contact with a temp much higher than that.

The entire cement floor acts as a radiator, and if its well insulated underneath, most of the heat radiates upward all the time. It is not like iron radiators, where water runs at 130-140 degrees, or baseboard hot water where it runs at 180 degrees, since those other systems have much less thermal mass. Radiators and convectors heat up relatively quickly, while a radiant floor may take days to come up to normal temperature.

Another item to check for is whether the system has an outdoor reset to make it more efficient. It is basically a thermometer that sends the outside temperature back to the boiler controls so that it can adjust the water temp based on the difference between outdoor and indoor temps. If its not very cold outside it will limit the temp of the water circulating in the system.

I have a gas boiler with cast iron radiators. My water temp is set to 100 degrees minimum and 140 degrees maximum. The boiler keeps the water temp at about 100 degrees all the time, and when there is a call for heat it starts the water pump and also fires up higher heat on the boiler at the same time. The pump and boiler flame will run constantly until the set temp on the thermostat, and then cycle off. It is not unusual for it to not reach the 140 max temp unless outside temps are below about 15 degrees fahrenheit.

Bruce

Half of the thermostats in our house are in one of the two mechanical rooms with sensors (ambient temp, ambient humidity, floor temp) in the rooms/zones. This is common practice and not at all unusual. In some cases this is purely aesthetic like not wanting a large thermostat on the wall of a nice wood paneled living room. In some cases it's more practical (though still aesthetic) such as w/ the conservatory where it will only be changed a few times per year rather than more routinely so no need to have it local.

Whether local or in the mechanical room it's the same thermostat. IAQ Redlink for forced air and Tekmar for radiant. The only difference is if remote sensors are connected.

I'm confused by the 'control hub' vs 'thermostat'. Every thermostat is effectively a 'control hub'? This whether a sensor is mounted within the same housing or is remote. The electronics and programming don't care where the sensor is? Electronics simply wants something to say what the current temp is so that it can compare that to the set temp and either turn a system on or off as needed.

Floor and ambient can each be set to a different temp.

How can I tell if it's short cycling (NTI Boiler btw)?

The system does have an outdoor ambient temp sensor.

In attempting to achieve a set ambient temp, how warm should it allow the floor to get?

How much difference should I expect between the sensor temp and the brick surface? And how does this vary by ambient temp in the room? The sensor is in the gyp w/ the tube so is approx 4-5" below the top surface of the brick.

Thanks All!

How can I tell if it's short cycling (NTI Boiler btw)?

Short cycling of the boiler would likely be a rising return water temp --- temp of the water going back to the boiler for reheat. This would also suggest the area or potential zone is not sized adequately. ( I am assuming this is a zoned set up? as in each sensor is it's own zone multiple zone valves that open and close based on sensor temp?

If water temps in boiler rise, boiler shuts off. If this is occurring frequently on and off, this is what short cycle means.

find out what the temps are of outgoing and return water temps.

I'm confused by the 'control hub' vs 'thermostat'. Every thermostat is effectively a 'control hub'?

If the thermostat in the mechanical room is indeed a thermostat then it's reading the temp in the mechanical room with a boiler in it. Some sensor type thermostats tend to average out temps from the main thermostat (the one in which you set the sensor set points)

This may be confusing the system. So it would be better if this was a control hub as opposed to a thermostat.

Some additional sleuth work is to see that all zone valves are open check in coming / outgoing temps before and after the zone valves.

Thanks. Some temp info this morning.

The main line feeding the manifolds. Interesting that the boiler says it's outlet temp is 154° and inlet is 144° and yet this line is much less than either. Too much return from the manifolds getting mixed in or this is normal?

And for those who like me like this kind of stuff!

If the thermostat in the mechanical room is indeed a thermostat then it's reading the temp in the mechanical room with a boiler in it. Some sensor type thermostats tend to average out temps from the main thermostat (the one in which you set the sensor set points).

I don't think so. Most thermostats that I've installed include connectors for remote sensors and then have either a hard switch or soft switch to choose to use the internal sensor, remote sensor or average. In this case the floor sensor is always remote and then it has a connector for a remote ambient sensor and it is currently set to use only the remote ambient sensor and it does indicate appropriate temps for the conservatory and not the mechanical room.

Is that a copper pipe feeding the gas input on the boiler? If it is then it needs to be changed to a black pipe.

you've clearly got some discrepancy to check out from the temp on the analog dial versus what the digital display is telling you. I would start there to see what gives.

Can you operate each zone independently from one another from the sensors... not that you want to do it but as a means of control?

I am a forced air guy they sell these thermostats with temp sensors thru out the home, the ducts have no dampers so say you want one zone really cool here they sell these sensors (typically wireless) but what happens is the system will just run and run or the sensors average out the temp. --- so in some cases at least in my world of forced air --- remote sensors aren't what they are cracked up to be.

So the easiest way is to see what 'control' you really have. Can you operate only 1 zone? What does the floor temp go to when you do that? (if you can do that) .

Our forced air is 6 zones controlled by 6 thermostats and each zone has a damper. These thermostats (Honeywell IAQ/Redlink) are either in the zone and use the internal sensor or in the mechanical room and use an external sensor.

In one case the thermostat is in the mechanical room and has two remote sensors (living room & dining room) and averages between these two.

In one case the primary zone thermostat is physically in one bedroom and also has two remote thermostats (not sensors but thermostats) in bedrooms on this same zone. These three can be set to average across them or give priority (absolute or %) to one. We are modifying this system so that each of the rooms will have an electric damper and so each of the three thermostats will then have more control over that individual room. Any thermostat can call for zone heat/cool and fully open it's damper while other thermostats can fully or partially close their damper as needed. We've also installed a barometric bypass (supply > return) to deal with high duct pressure when some dampers are closed.

Hydronic has 13 zones and 13 thermostats (and 13 valves) so yes, each zone controlled individually. Similar to forced air, some thermostats are local and some in the mechanical room. ALL floor sensors are remote sensors (by simple necessity). Thermostats in the mechanical room have remote ambient sensors in their zone.

This morning the only zone calling is the conservatory. However, two bathrooms will occasionally call as they are maintaining a minimally (70°) warm floor.

The question is: does your hydronic system have this kind of control?

You know where you only call one zone to come on. Can you do that or no? It may give you further insight to your problem / like if the one zone reaches your set point... then if you have the control of the hydronic zones in this fashion open another hydronic zone.

Does the floor in those zones hit the desired temp? Assuming you have the control of the hydronic system in this fashion.

I see two grey expansion tanks. I'm assuming one if for the hydronic heat and one is for domestic hot water. Check the model numbers and make sure that the one on the domestic hot water is made for that. Our boiler expansion tanks are grey but the domestic hot water one is blue by Pro Flo. Amtrol's one may be white.

Your picture does not seem to show the manifold with the analog gauge. However, the difference in temperatures between the digital and analog gauges may be because you have a mixing valve in between the two systems. When a boiler runs at 150+ degrees that is too high for in-floor heat, so they install a mixing valve that brings in cooler water to get it down to the temp needed for the in-floor heat.

After seeing a picture of your system and reading your explanation of how it works, I recommend you find a good HVAC contractor and make him/her your friend. It looks like you have a very professional installation, but its way more complicated than a simple boiler system with heat convectors. You need a contractor who understands the technology that was installed and will spend the time to fix or tune your system.

The issue you are having may be something as simple as a temp sensor that is feeding back the wrong temp, or a control valve that is not opening properly to send hot water. However, somebody onsite needs to go through that troubleshooting.

Bruce

Hydronic has 13 zones and 13 thermostats (and 13 valves) so yes, each zone controlled individually. Similar to forced air, some thermostats are local and some in the mechanical room. ALL floor sensors are remote sensors (by simple necessity). Thermostats in the mechanical room have remote ambient sensors in their zone.

This morning the only zone calling is the conservatory. However, two bathrooms will occasionally call as they are maintaining a minimally (70°) warm floor.

Ok if that's the case sounding more and more like capacity issue as I originally thought.

One way to possibly shed light on this is when it's colder and you have more zones calling and not reaching temp would be to shut a zone or two down that are calling to see if the other zones then reach temp. In essence you're redirecting the heat to those zones. If they reach temp or temp starts getting closer to set point it should indicate the capacity issue.

The other is that hydronic heat is a slow and gradual thing so recovery times are longer, unlike forced air.

I have a 4 zone forced air inverter (multi speed) heat pump as an example, each zone controlled by dedicated thermostat in that zone - no remote sensors --- for simplicity sake if some one is in that zone (area of the structure) they simply go to that thermostat to dial in the temp they want. If you have a system with remote sensors then you have to find the thermostat that controls those sensors. (much more complicated, not that hydronic with 13 zones wouldn't be complicated... so kind of a misnomer.)

The advantage to a zone system is cutting expense / limit cooling & heating in areas not in use. I can shut the system off completely if I want and recovery times are extremely short when running a single zone. Typical recovery times can be 15 min depending on various load conditions. As opposed to a traditional AC with a single stat, it could be up to 4 hours recovery time.

The other advantage is cooling or heating where you want it when you want it. Comfort means different things to different people so in terms of residential you have the benefit of making everyone comfortable according to what they want. Someone says 70 is too cold, someone says 78 is too warm. If you only have one thermostat it leads to thermostat wars.

Zoning is accomplished in more than one way, but started in the commercial realm. If areas of a commercial building are unoccupied it makes little sense to spend money to heat and cool those areas. Then building management systems took hold to remotely control these aspects from anywhere in the world (more or less). But these kinds of controls aren't with out their own set of trouble. The control is only as good as how it's implement / ease of use / it doesn't negate on site inspection and investigation to make sure the systems are functioning properly.

That said given the complexity of this system I concur with Bruce in that you need to find a good hydronic heat man to go thru this system with you.

I have been following this thread from time to time and have been hesitant to comment; I still am.

However you have included some pics; from what I see, it seems that you have an NTI Trinity Tft110 Hydronic boiler probably operating in a building with 3-floors including a basement.

I hope that I just misunderstand the situation but from the pic of your mechanical room I see little evidence of hydronic design ‘Best Practices’. There seems to be no documentation left at or near the NTI boiler, such as an Owners Manual or ‘Installation Manual’, no labeling of components or direction of flow arrows (Supply/Return) on any of the piping. Do you have an, ‘As Built’ document or book that in detail describes the design, operation, flow, commissioning process with all relevant temperatures, pressures, fluid levels and composition, electronic settings (schematics) etc for this system? A technician that has never seen your system should be able to walk in cold and after 10 or 15 minutes of studying the documentation should have a pretty good understanding of what’s going on and how this system should function when properly operating - if it was designed properly to begin with, rather than spending hours of his time and your money to just scratch his head. All systems are unique and custom built - they all need their ‘Road Map’ and service records within sight to be found and understood without guessing or assuming!

It’s somewhat unusual to see 2-expansions tanks. What might be the reason for that; 1 for the boiler system & 1 for the in-floor radiant (just guessing)?

I see no obvious ‘Primary - Secondary’ piping of the boiler - that “NTI Strongly Recommends” (Pg 44 Installation & Operation Manual For Trinity Tft Boiler). As well your system also seems to look nothing like fig. 10-5 or 10-6 of the installation manual (pg 48 & 49). Neither do I see a hydro separator, buffer tank nor any method of ‘magnetic dirt separation’ to capture microscopic ferrous metal particles entrained in this system’s fluids. Perhaps your system doesn’t require them.

I would take ‘Bruce in Northern Virginia’s advice:

“After seeing a picture of your system and reading your explanation of how it works, I recommend you find a good HVAC contractor and make him/her your friend. It looks like you have a very professional installation, but its way more complicated than a simple boiler system with heat convectors. You need a contractor who understands the technology that was installed and will spend the time to fix or tune your system.”

I would look for a professional mechanical engineer that specializes in efficient hydronic design & installation.

Your system ‘looks' overly complicated without the fundamentals of efficient design.

I’m hoping I’m wrong.

YMMV

NTI Trinity Tft Series Installation & Operation Manual

IMPO

SR

Thanks all!

Might take me a bit to fully respond, but here's part I.

Switching HVAC contractors would be difficult at this point. This is a new build (we've been in for about 3 months) and this is our builder's chosen HVAC contractor. There are numerous issues with them but for now we need to dance with who we came to the party with and try to make the best of it*. We need to try to figure out what the problems are and give them an opportunity to correct them.

The analog gauge is just to the right of the boiler. And yes, there is a mix valve directly below (upstream) of it.

There are actually 3 grey expansion tanks. One (lower left) is for the primary hydronic loop. One (right) is for the snow-melt loop (separated from the interior hydronic loop by the heat exchanger below and to the left). The third one is not pictured but is in the boiler supply line to the side-arm domestic hot water tank.

The building is 4 levels: (LL (partial walkout), Main, 2nd and Loft). More: https://bamasotan.us

There is limited direction of flow marking on the hydronic system with a sharpie.

There is no commissioning document with the temps, etc. Email sent.

More later after an upcoming conference call...

-----------

* Some of the issues w/ our current HVAC contractor include:

- Three exhaust fans are underperforming because of poor flex duct installation. We asked for rigid but were told that it would be difficult for the runs and that they'd make sure that the flex performed as well as possible.

- We asked that ERV stale air to be taken from baths and fresh supply ducted to bedrooms. They did not do that. When this was noticed and pointed out to them it was too late to change. They did agree to upsize the ERV's. Not as good a solution but should help. Due to Covid we've not yet had many people here so we don't yet know how CO2 levels at night will do.

- Our son & DIL's bedroom does not have sufficient ducting. Another duct will be added next month to provide better airflow, cooling and heating in their room. This will be a somewhat major project involving a lot of ripping out and redoing of sheetrock and trim. Very irritating for a new house.

- Returns in bedrooms were supposed to be high-low but were not done that way. For those not familiar a high-low return has the return duct run vertically in a wall cavity with a vent near the ceiling and another near the floor. The one near the floor has a register flapper that when 'closed' causes return air to be pulled from the ceiling, when open has it pulled from near the floor and otherwise a little from both.

I want to hire fsq4cw. But unless he lives in Denver (do you fsq4cw?) I can't.

We had our system redone 4 years ago. Just last week I went downstairs and found zero pressure on my radiant floor heat. I hunted around and found the Amtrol Ex-30 tank had rusted through and was leaking. I called the installing company to come replace it under warranty. I sent pictures of the rusted out portion and the whole tank so they can bring it and replace it in one visit. So they didn't bring it and it takes 2 visits. This always happens so I should not be surprised.

When they finally bring the tank I reminded my husband to have them fill up the pressure from the air valve to 20 psi which is what the system is pressurized at and it is clearly labeled on the dial. The tech tells him that they don't do that, they just put them in and it isn't needed. My husband says he doesn't want to argue with the professional. After he leaves and I found out the tank was not pressurized properly I pull the instructions for the Amtrol Ex-30 that shows this must be done. I download a youtube video showing how to do it after it is installed. We isolate the tank, depressurize it by draining the system, pressurize it and then refill the system.

In finding the instructions I find out there is the Amtrol RX-30 that has a plastic liner that is to be used for radiant snow melt and non-oxygen barrier tubing applications. I order two of them and we will be replacing both our EX-30s (one snow melt and one radiant floor heat) with the RX-30s ourselves.

If you look at the Amazon reviews of the EX-30 there are other people with them rusting through in 1-4 years. Ours rusted through at 4 years. I don't know if they all have them on snow melt or older non-oxygen barrier tubing like us. But I can say that even after a short time the EX-30 is loaded with rust.

Our contractor also installed the wrong size Amtrol EX-30 on our boiler system that is 225 btu and had to pull it for the Amtrol EX-60 since the pressure was all over the place. Even though it was only on for a short time we can see it is loaded with rust as it is still in our basement.

Our old boiler had a Honeywell expansion tank that lasted over 20 years so not impressed with the Amtrol EX-30.

Will your contractor buy and replace both tanks? Probably not. But you should get at least the snowmelt one replaced because it is the one for snow melt. He may buck against the other one. And I'm not sure that will even be a good part. I don't know how long it has been in their line-up but it was probably introduced due to the failures of the EX-30 on snow melt and non-barrier tubing. Hopefully Amtrol did a better job on the RX-30 than the EX-30.

Edit: Just reread your post and you have a grey expansion tank on your side arm. That needs to be a potable water expansion tank if it is on the potable water side. Otherwise it will rust into your potable water supply. We also have a sidearm hot water tank and there is a check valve on the supply from fresh. That is why we have the potable water expansion tank on that line. The heated water from the boiler is on the same line as the boiler expansion tank so does not need it's own.

Sorry friend, you fall into a pattern for me. I've encountered plenty of individuals in my lifetime, back to childhood, who like to make up facts to suit their needs and pretend they know what they're talking about. You may have too but didn't recognize them. Such people also seem to like to boast as you do.

After choosing a general contractor, choosing an HVAC contractor is one of the most important steps in building a house. To use "the general's choice" is too often a mistake, one you made that's too late to change for the original build. Stand back, give the bungler a chance, and don't hesitate to hire another if the situation isn't remedied, especially considering advice and undone work mentioned by fsq and others.

OP, the red arrow on the outside dial in your first picture is usually rotated to show where the pressure is supposed to read. It is a static marker that you would reference to be sure your pressure is reading what it should.

@mmmm12COzone5, thanks for the tips on the tanks. The snowmelt is an EX-15 so I'll have to check to see if that s/b an RX. The grey (EX-15) tank on the hot water is on the boiler loop, not potable so s/b OK. There is also an ST-5 and check valve on the potable cold water supply to keep hot water in the tank from backing up in to the potable cold water.