Trying to Make Temp...

[CaptainK]

Ok, so first real heating days of the year, some things I was not expecting, and a few questions.

Today, no solar gains (overcast) boiler is tooling along, house is set at 70, but is maintaining 69. Can't seem to get above that yet. Long story short left a window open last night and the house went down to 67. Closed window at 4:30 am. It is now nearly 10am and we are still not up to temp. Is this normal for a radiant system?

Boiler is running near constant holding ~165 radiant loop temp is set to 135 at the mixing valve, and is at 120 at the distribution header. Floor temps are ~75 +-5. Under any area rugs temp is about 100.

So other than keeping windows closed during winter, any ideas if is this normal, it seems slow to recover, or am I just too impatient?

Last night low was 22, currently we are at 34 with overcast.

 

[Armaton]

What material floor? My 1782 sf basement, carpet and tile covered cement, heats from start of season in about 12 hours. Two zones 3 loops each 110 degree water pumped by a 15-58FC for each zone. Can lay on the carpet and feel the heat so I would say you may have a water flow problem. If you are pumping 120 degree water through your zones your floor should be toasty.

 

[CaptainK]

Hardwood, old, thick, PEX with extruded aluminum spreaders installed under sub-floor (retro-fit). Floor was warm, it took till about 13:00 to make temp. which based on your description sounds reasonable. Temp over shot by 1 degree, and has not fired since it is now holding about 70 in the house but feels cool.. and the floor is back to cold. So if that happened last night, in combo with the open window I can understand the dip.

Now as far as preventing the dip... ideas? I have heard of thermostats that have a floor sensor to keep the floor at temp regulated but I'm not sure this is will help. Then again as the weather gets colder maybe it will be a moot point.... maybe?

 

[CaptainK]

The plot thickens... Sat. Morning, cool at 4am... thermostat shows 68 (set to 70) but no call for heat... I check the settings in the thermostat, just to be sure its set for 70 and it is. When I leave the menu and it goes back, it clicks on... Took till about 9:30 to recover to 70 Strange.

Also found that when there is a call for DHW the temp going out to the radiant loop (set normally at 130) drops to 110 Think this might have something to do with the flow of the pumps and the mixing valve for that zone.. but not sure. For the time I have "fixed it" by setting the DHW zone to Priority. So when it runs it shuts down all other zones till it makes temp then resumes. Will see how well that works.

 

[huffdawg]

thermoststat might have 2 or 3 degree deadband.. won't call for heat until drops below 68

 

[CaptainK]

thermoststat might have 2 or 3 degree deadband.. won't call for heat until drops below 68

Thought of that, but if that is the case it's very inconsistent, I have heard it click on and checked it, it will be at temp, it just decided to go for some reason, like it can read 10ths of a degree but does not show them, I seriously doubt this is the case. Maybe I should invest in a Nest, or go other direction and get an old mercury switch thermostat

 

[maple1]

The plot thickens... Sat. Morning, cool at 4am... thermostat shows 68 (set to 70) but no call for heat... I check the settings in the thermostat, just to be sure its set for 70 and it is. When I leave the menu and it goes back, it clicks on... Took till about 9:30 to recover to 70 Strange.

Also found that when there is a call for DHW the temp going out to the radiant loop (set normally at 130) drops to 110 Think this might have something to do with the flow of the pumps and the mixing valve for that zone.. but not sure. For the time I have "fixed it" by setting the DHW zone to Priority. So when it runs it shuts down all other zones till it makes temp then resumes. Will see how well that works.

I think I would rather have 110 water going through my loop than none in those periods.

Also think I would start at a slightly warmer temp on the thermostat than what you would consider 'normal', then after a few days, every couple of days, go down a degree at a time & see how things react until you get to where it seems to feel not warm enough again. Radiant is slower to respond/recover, and takes longer to get things up to temp - but it's beauty is even heat. One more thing you might try is to lower your loop temps by say maybe 10° so it will circulate longer therefore maybe reduce the periods of time it sits there not moving & cooling off. The folks here who have systems based on constant flow but varying fluid temps (varying with heat loss - outdoor temps - 'outdoor reset') seem to be a very satisfied happy bunch.

 

[flyingcow]

I run my staple up between 125/130. I've got a good inch of plywood plus ceramic tile. Any lower, doesn't seem to work as good.

 

[huffdawg]

Keep in mind a heated floor does feel cold to your feet a lot of the time, body temp is around 98 I think. You step on a 80 floor and it does feel cold.

 

[CaptainK]

I have been contemplating boosting the loop temp but am wary due to the hardwood floors, I had not considered lowering the temp to have longer run times... I thnink I will give that go, we are going to have some more cold weather next week, Ill see how it goes. As for getting the flow to change temp with the outdoor temp I'm guessing I need a special mixing valve? Does it get tied into the boiler (or rather does it communicate with the boiler)or is it stand alone?

 

[CaptainK]

Keep in mind a heated floor does feel cold to your feet a lot of the time, body temp is around 98 I think. You step on a 80 floor and it does feel cold.

When I say feels cold I mean the air feels cold. After living with FHA so long having the floors at 80 feels divine!

 

[flyingcow]

Is your radiant floor controlled by just a t- stat?

 

[CaptainK]

Yes.

 

[JP11]

My staple up runs 140 to 145. In the cement runs 110.

No aluminum plates at all. just 1" air space then 1.5 inch foil faced foam below that.

JP

 

[CaptainK]

My staple up runs 140 to 145. In the cement runs 110.

No aluminum plates at all. just 1" air space then 1.5 inch foil faced foam below that.

JP

Type of flooring? I was told to keep temps low to avoid damaging the hardwood flooring.

 

[JP11]

All ceramic tile and laminate wood.

 

[Medman]

It just may be your thermostat - I had one go bad and it did the same thing - acting erratic and not controlling temp properly. I invested in a good Honeywell multistage and haven't had problems since.

 

[flyingcow]

here's my thoughts.my radiant floor is only 25 percent of my first floor of my house. this is in my kitchen in to keep the feet warm from the ceramic tile. but does help a lot in the spring or fall of the year in heating the house.I had plans a few years ago to do my whole first floor and staple up radiant.if I was going to do that I would have had a control system were it would have measured the outside air temperature, the inside air temperature and a mixing valve that would have adjusted off either the tank temperature or the boiler temperature.

just a wild guess but you're not going to get much of a temperature swing inside of 12 hours off just a t-stat that tied into radiant floor.

also this is a question for heaterman, or others in the heating business. if it's not new hardwood flooring does it really matter on the temperature of the floor?130/140 should be ok?

 

[flyingcow]

My above post was voice to text. Rough sounding. Hopefully makes sense.

 

[Armaton]

My thermostats for my in floor will kick my pumps on for 2 minutes every 24 hours so the pumps won't seize during the non heating season, maybe that is what yours is doing when it cycles with no call for heat? Just a thought.

 

[flyingcow]

Also, basically from nov to april me in floor heat is on all the time. I leave it on, obviously because it's not my main source of heat, i can do that. But, if i did have an all radiant floor, it would be set on something different than a t-stat?

 

[CaptainK]

It just may be your thermostat - I had one go bad and it did the same thing - acting erratic and not controlling temp properly. I invested in a good Honeywell multistage and haven't had problems since.

I think I'm going to swap it out for another one (we have two identical, one for each zone) and see how that works. It just kicked on for about 5 min and shut down again. I'm starting to think that this thermostat is flaky...

 

[CaptainK]

.....also this is a question for heaterman, or others in the heating business. if it's not new hardwood flooring does it really matter on the temperature of the floor?130/140 should be ok?

I have been trying to find that out myself... the answer has been quite elusive.

 

[maple1]

I think you should key on your floor temps & not supply water temps. 75 might be a bit too low - from the Googling I did (how'd we survive without that little tool?), seems floor temps are recommended to be at around 85° no matter what the floor is made of. Area rugs might complicate the issue, but shouldn't that much if they aren't that big. Plus one floor system would produce a hotter floor than another, even with the same supply temps - due to variations in how they're done & heat loss underneath, etc.. I'm not so sure about the damage to hardwood floors aspect either. That would come from changes in humidity and not temperature. It is usually drier inside in the winter than summer - but that situation would apply whether there was heat in the floor or not. So I think I would aim for 85° floor temps (slowly working up), and monitor interior humidity levels to keep those at normal levels.

Those aren't my floors though.

 

[CaptainK]

I think you should key on your floor temps & not supply water temps. 75 might be a bit too low - from the Googling I did (how'd we survive without that little tool?), seems floor temps are recommended to be at around 85° no matter what the floor is made of. Area rugs might complicate the issue, but shouldn't that much if they aren't that big. Plus one floor system would produce a hotter floor than another, even with the same supply temps - due to variations in how they're done & heat loss underneath, etc.. I'm not so sure about the damage to hardwood floors aspect either. That would come from changes in humidity and not temperature. It is usually drier inside in the winter than summer - but that situation would apply whether there was heat in the floor or not. So I think I would aim for 85° floor temps (slowly working up), and monitor interior humidity levels to keep those at normal levels.

Those aren't my floors though.

Yes the idea of having to replace the flooring is not that appealing to me. I know the house is overbuilt, the plaster walls are backed with 1/2" concrete board then have a slathering of about 3/4" plaster (found that out trying to cut an access hole for a wall mount tv, must have used 5 dremel bits) the floors are interlocking boards on the subfloor and then hardwood on top, If I remember the subfloor is about 3/4" and the flooring is another 3/4" that seems like a lot for the heat to get through. So perhaps a tweak of the supply temp is required.

EDIT (forgot to add we are near a river so the house is always humid, we have a big dehumidifier in the basement to help keeps things from getting... fuzzy....) yes, it runs year round.