Troubleshooting My Propane Fired Radiant Heating System

[teejk]

I'm busy learning about radiant floor heating as I prep to build a house this spring... We're planning to just do the basement floor at present, and we'll heat upstairs with wood or pellet stove. We won't be able to close off the basement from the upstairs, so I'm planning to use a floor temp sensor or two in the basement, rather than traditional thermostats.

From what I've read, the only real issue I see with your setup is that you're running a zoned system where you shouldn't be... Your "solution" is how it should have been set up from the beginning, since you don't want to close doors. Zones generally either need to be really large, or more or less sealed to work well. Your problem may be compounded by thermostats that don't quite agree on the temperature, biasing the bedroom zone to run all the time because it thought the temp was a few degrees cooler...

Bottom line: I don't think a zone setup is going to work well if you're not going to close doors to separate the zones.

I think also you keep saying "plumber" when you mean HVAC guy?? A plumber is generally NOT a HVAC expert, but is good at ensuring poo flows downhill, and the hot is on the left, cold on the right... If you hired a Plumber to install your heating system, you may be at least partially responsible for your troubles...

I'm 43, and I usually find that when I have problems, it usually IS my fault...

1stDuece...my installer was a master plumber AND an experienced HVAC guy. IMHO you need a plumber on a modern system because there is a lot of plumbing involved...beyond the system design (zone layout, T-stat location, etc.) I'd venture to say that it is all plumbing. As for zones, I believe that is the beauty of radiant heat...heats objects instead of air so zone bleed-through is not a big deal like it would be in a forced air system. We ran a rather unconventional system with suspended tubing and we did isolate the zones in the joist spaces (foam board) and insulated the bottom of the joist spaces (essentially creating an air pocket with the tubing suspended in the middle). It works as designed other than the modulating boiler (on-demand tank-less) struggles to keep up in really cold weather. It does fine in "so-so" cold weather and suffers in not so cold weather when the computer kicks in.

 

[Rustyiron]

I don't have any direct help for Hillstreet (sorry) but I have a radiant, mostly in slab with a small portion in the ceiling with the plates. It's fired primarily with a wood gasification boiler with a manual oil backup. It is my first experience with radiant heat. Being a lifelong building contractor and an absolute "do it your self" type, I still actually hired out the radiant design. The only other hired help in the whole building was the concrete foundation & flat work. I worked with the design people and they provided me with drawings that allowed me to do the whole installation my self. From the tubing to the manifolds & connections, mixing valve's, expansion tanks, air separators, pumps etc. the whole thing. It is an added pleasure to look at my "wall'' with all of the above mounted to it an understand what each component is and should do.
I can sweat a pipe, but am not a plumber or HVAC guy! I am completely happy with the system and it's performance. Hillstreet, we have some fancy "Tecmar" t-stats with a floor (slab) sensor that does something with the floor temp & the room (air) temp.
At the time being so busy, I'm not sure what they cost, but all the design fee's were taken off the part's & materials that they supplied (at my choice). I did "check" them several times against internet suppliers and they were right inline. I guess what I'm trying to say is that although radiant is simple, there is no second chance at a lot of these things, and what changes you can do later could be expensive. Consulting a professional radiant designer is (coming from a cheap bastard) well worth it (in comfort) and being able to install it myself saved thousand's of dollars.

 

[HillStreet]

Thanks Rustiron,

This design is probably more than I need with all the pumps and all. I like the header idea because it attenuated any difference between DHW and heating loops. And, I have had PLENTY of hands on work building houses as in my younger days I would frame, roof, siding, electrical, Sheetrock, paint, garage doors, even masonry chimneys. On this house, we closed on the land on October 29 and I was very fortunate to get the concrete guy to pour before freeze. (He had work lined up but his builder could not get permits, so he came straight over to my job). The other guys, excavator, framer, electrician, sheet rocker I have known for a long time and they did accommodate thankfully. As you know, if you're not in the ground in Maine by end November you will wait till May. It was a light winter though so we went for the winter build.

I do think all this equipment functions ok, it just needs a tune up. I can do that with patience and reading. My thermostats for instance are Uponor just heat, but they do not overrun, they are accurate. The plumber just wasn't thinking about the system as a whole. Nor did he show any interest in balancing anything.

 

[HillStreet]

dadster4,

I will certainly reference the manual. I'm retired and it's winter, what the heck, need something to do. I will keep excellent notes so I'll not get lost.

The supply and return pipes are connected at the end where supply turns into return. There is a quick turn valve in the end, set at about 1/2 open. The supply loop and return loop tees off to the mixing valve, then the mix goes to the circulator, that goes to the manifold.

I will lower the heating setting in the boiler to 150 degrees, and I will set the mixing valve to 140 degrees. The "controller" you refer to I assume is integrated into the boiler. I have a Taco 4 position electrical box where the t-stats, outdoor sensor, DHW sensor, and circulators all connect but that is just electrical connections. I will read the boiler manual.

The regulator was checked by the propane company. One guy here several hours while the plumber adjusted the vent stacks (some harmonic imbalance that had to be corrected. Plumber did offer that it "was not my fault".

I do appreciate all the effort from you guys, it is a big help to me. I am able to comprehend these things but do need input from you folks. I really don't know what the run time should be but know if it runs 80% of the hours when the sun is down it is way too much.

 

[HillStreet]

teejk,

My system is much simpler than yours, but the plumber went wild with pumps and zones. Once it is adjusted it will be fine I am sure. dadster4 as you can see has me directed toward control temps. That could be delayed a bit while I burn coal to get through this cold snap. I will study meanwhile.

Zones in this house I believe are not a wise idea. I walk from the living area to the bedrooms and have to open/close doors? Nah, that is why I disconnected the t-stat in the bedroom and connected the circulator to the main zone.

 

[HillStreet]

I'm busy learning about radiant floor heating as I prep to build a house this spring... We're planning to just do the basement floor at present, and we'll heat upstairs with wood or pellet stove. We won't be able to close off the basement from the upstairs, so I'm planning to use a floor temp sensor or two in the basement, rather than traditional thermostats.

From what I've read, the only real issue I see with your setup is that you're running a zoned system where you shouldn't be... Your "solution" is how it should have been set up from the beginning, since you don't want to close doors. Zones generally either need to be really large, or more or less sealed to work well. Your problem may be compounded by thermostats that don't quite agree on the temperature, biasing the bedroom zone to run all the time because it thought the temp was a few degrees cooler...

Bottom line: I don't think a zone setup is going to work well if you're not going to close doors to separate the zones.

I think also you keep saying "plumber" when you mean HVAC guy?? A plumber is generally NOT a HVAC expert, but is good at ensuring poo flows downhill, and the hot is on the left, cold on the right... If you hired a Plumber to install your heating system, you may be at least partially responsible for your troubles...

I'm 43, and I usually find that when I have problems, it usually IS my fault...

Huh? Hot on left, cold on right? Is that a new concept? I'll have to run that by my plumber. Just kidding!!!

 

[Raspy]

HillStreet,

It sounds like the first thing to do is understand the control strategy of the boiler. The domestic hot water should be a separate function from the central heat. The DHW usually has priority and runs at a higher boiler temperature.

So, set the CH function to the desired delivery temperature and set the DHW at it's default temperature (the temperature fed to the heat exchanger). This might be about 180 degrees to the DHW. The radiant delivery temperature probably doesn't need to be higher than about 130 degrees in your case, although you have a lot of insulating floor material.

It sounds like the tempering valves are useless in this case and may just as well be eliminated. However you do seem to get enough heat now that the thermostat problem is fixed.

Do not try to control it by measuring the floor temp! Your room thermostats will do a fine job if placed properly.

Eliminate the outside sensor and find where to tell the boiler to not use it. This is not needed because your control strategy is just on or off at the thermostat and not a constant circulation system.

It seems some on here think a computer control on a boiler is some kind of conspiracy, but the fact is they make the boiler much more efficient and easily able to handle multiple functions.

The theory is the boiler will come on strong and then throttle back as it approaches the designed floor delivery temperature. The computer allows this and promotes condensing where the efficiency will rise about 10%. Older boilers only know off or on. Imagine how it would be if you drove your car at full throttle all the time and adjusted the speed by turning the key on and off! Very low efficiency and always uneven speed. Older boiler operate this way. Modern, condensing boilers throttle to match the load.

BTW, modern boilers are NOT tankless water heaters. So comparisons of the two are invalid.

To recap: Go into your settings program or display. Select Central Heat, CH. Select setpoint control (thermostat). Switch off outdoor reset or outdoor sensor, or just disconnect it. Select the CH temperature (probably 130 degrees for starters). Select DHW. If your DHW tank has a sensor that talks to the boiler, or a snap switch that talks to the boiler, set the boiler temp for 180 degrees. If the boiler temp is the domestic temp with no separate stand alone tank, set the temp at about 140 for starters. Go to the tempering valves and either get them out of there or open them up to where they are not restricting the flow (I suspect they are not causing too much trouble because you are getting heat).

Don't worry about the number of boiler cycles at this point because you have had other problems that will cause that.

Last thing is, in your quest to get your thermostat situation fixed, DON'T buy a Nest thermostat. If you need to go back to two thermostat zones, get a remote one as previously suggested or route a new wire to a more sensible location. Good work on your thermostat trouble shooting.

The only time you might use a floor sensing thermostat is if you have a radiant system inside a forced air zone, such as a bathroom inside a larger forced air heated zone. Floor sensing is not for general use because it cannot take into account the room temperature that is influenced by other factors, so it cannot make a room a constant temperature. Further, setback thermostats can be used as switches which will give a blast of heat at strategic times, like an hour before you get up, and then settle to temperatures that are right for you at various times.

 

[HillStreet]

Thank you Raspy. I am going to read the manual for resetting these parameters. I guess I will make the changes while the coal stove is running so in case I screw it up I will have heat.

 

[teejk]

Thank you Raspy. I am going to read the manual for resetting these parameters. I guess I will make the changes while the coal stove is running so in case I screw it up I will have heat.

You are in Maine! How deep is your new snow? A traditional system would be a boiler connected to a relay (like a Honeywell) that would be started by a call from your T-stat...that relay would send signals to your boiler and your circ pump(s). If it ain't working, then I think the pros would start at the T-stat. Your relay should not close until that thing says the T-stat no longer wants heat. That would involve location (like in a area where it was getting heat apart from your system like sunshine or other heating). You are running DHW so you have mixing valves and such that I don't...my guy refused to use that and put in a free-standing LP fired water heater instead. So while I have more zones, my system is actually pretty simple.

 

[teejk]

HillStreet,

It sounds like the first thing to do is understand the control strategy of the boiler. The domestic hot water should be a separate function from the central heat. The DHW usually has priority and runs at a higher boiler temperature.

So, set the CH function to the desired delivery temperature and set the DHW at it's default temperature (the temperature fed to the heat exchanger). This might be about 180 degrees to the DHW. The radiant delivery temperature probably doesn't need to be higher than about 130 degrees in your case, although you have a lot of insulating floor material.

It sounds like the tempering valves are useless in this case and may just as well be eliminated. However you do seem to get enough heat now that the thermostat problem is fixed.

Do not try to control it by measuring the floor temp! Your room thermostats will do a fine job if placed properly.

Eliminate the outside sensor and find where to tell the boiler to not use it. This is not needed because your control strategy is just on or off at the thermostat and not a constant circulation system.

It seems some on here think a computer control on a boiler is some kind of conspiracy, but the fact is they make the boiler much more efficient and easily able to handle multiple functions.

The theory is the boiler will come on strong and then throttle back as it approaches the designed floor delivery temperature. The computer allows this and promotes condensing where the efficiency will rise about 10%. Older boilers only know off or on. Imagine how it would be if you drove your car at full throttle all the time and adjusted the speed by turning the key on and off! Very low efficiency and always uneven speed. Older boiler operate this way. Modern, condensing boilers throttle to match the load.

BTW, modern boilers are NOT tankless water heaters. So comparisons of the two are invalid.

To recap: Go into your settings program or display. Select Central Heat, CH. Select setpoint control (thermostat). Switch off outdoor reset or outdoor sensor, or just disconnect it. Select the CH temperature (probably 130 degrees for starters). Select DHW. If your DHW tank has a sensor that talks to the boiler, or a snap switch that talks to the boiler, set the boiler temp for 180 degrees. If the boiler temp is the domestic temp with no separate stand alone tank, set the temp at about 140 for starters. Go to the tempering valves and either get them out of there or open them up to where they are not restricting the flow (I suspect they are not causing too much trouble because you are getting heat).

Don't worry about the number of boiler cycles at this point because you have had other problems that will cause that.

Last thing is, in your quest to get your thermostat situation fixed, DON'T buy a Nest thermostat. If you need to go back to two thermostat zones, get a remote one as previously suggested or route a new wire to a more sensible location. Good work on your thermostat trouble shooting.

The only time you might use a floor sensing thermostat is if you have a radiant system inside a forced air zone, such as a bathroom inside a larger forced air heated zone. Floor sensing is not for general use because it cannot take into account the room temperature that is influenced by other factors, so it cannot make a room a constant temperature. Further, setback thermostats can be used as switches which will give a blast of heat at strategic times, like an hour before you get up, and then settle to temperatures that are right for you at various times.

Justy for the record, modern boilers are essentially "tankless"...they might hold a few gallons but nowhere near what the hydronic expert (hydronics institute or something like that) wants...I went through that argument with my installer and I lost...no sense keeping a large tank of water hot if the house didn't need it (even though in my shop he installed a tank system).