Different temps in each bedroom

[bentz69]

Second floor of the house has 4 bedrooms that all see different temperatures. I will list the specs of the bedrooms below. 1st bedroom is currently empty but will likely be a babies room. 2nd and 3rd bedrooms have a 11 and 15 year old and the 4th bedroom is the master. A Nest thermostat for heat only is located in the master. We have a Burnham v84 oil boiler for baseboard heating and hot water that is set to 195°. There are 3 zones (basement, 1st floor, 2nd floor) each with a new Taco 007 pump and Taco 3 zone relay. Each floor has nest thermostat. Hardwood floors throughout the whole house and no carpet.

The kids have been saying that their rooms have been cold so I placed a temperature sensor in each of the 3 bedrooms. After checking each sensor and the master bedroom thermostat numerous times throughout the day for the past 2 weeks, I discovered that the 1st bedroom is always 4° colder then the master. The 2nd and 3rd bedrooms are always 3° colder then the master. This may not seem like a big difference BUT, we leave the thermostat set to 66-67° which is comfortable for all of us during the day and night. 63° to sleep is too cold for the kids.

I pulled the covers off every baseboard. I confirmed the fins are all oriented correctly, straightened any bent fins, vacuumed all the dust/debris, and sprayed the fins with vinegar/water mix to clean them. There are no obstructions or any items blocking the bottoms of the baseboards and all baseboards are fully open. I also confirmed that every baseboard is full of fins from end to end with no bare pipe.

We moved into this house about 3 years ago. Last spring I changed all 3 circulator pumps and installed the 3 zone relay to convert the line voltage system to 24v for the new Nest thermostats. At that time, the basement and 1st floor had old Taco 007 pumps and the 2nd floor (where the bedrooms are located) had a Armstong Astro 230ci 3 speed pump set to speed 2. Now every zone has new Taco 007.

I believe the loop runs like this. Master bedroom to 1st bedroom to 2nd bedroom to 3rd bedroom to hallway bathroom to master bathroom to master closet back to boiler. I took some temp readings with the infrared gun directly between the fins. I was reading roughly 155°-160° in the master bedroom and between 140°-150° in the other bedrooms.

I have read about covering a section of fins with aluminum foil which sounds like an easy fix for the master bedroom. But, if the baseboards are undersized for the other bedrooms then I would like to have that fixed. Especially the 1st bedroom if we plan to have another baby.

Is it possible that the Taco pump is not powerful enough for the 2nd floor? I could swap the Armstrong pump back in and turn the speed up if that would fix the problem.

Any ideas?

1st Bedroom - 111 ft2 / 892 ft3 - 4' of baseboard
2nd Bedroom - 148 ft2 / 1184 ft3 - 8' of baseboard
3rd Bedroom - 156 ft2 / 1251 ft3 - 8' of baseboard
(Master) 4th Bedroom - 275 ft2 / 2200 ft3 - 14' of baseboard

 

[Fitter30]

Nest thermostat did you set it up for hot water heat? Normal design of baseboard loops is 20* -30* difference between supply and return. Guess you measuring fin temp. Shut off some of the fin tube in master to give the thermostat a longer run time. Single pipe 3/4" fintube 195* 700 btu's a foot. 3/4" single tube fin tube 1 95* water 700 btu's

 

[Sponsor]

 

[bentz69]

Nest thermostat did you set it up for hot water heat? Normal design of baseboard loops is 20* -30* difference between supply and return. Guess you measuring fin temp. Shut off some of the fin tube in master to give the thermostat a longer run time. Single pipe 3/4" fintube 195* 700 btu's a foot. 3/4" single tube fin tube 1 95* water 700 btu's

Yes the nest is setup correctly.

Supply temps are 160-170 when measured at the beginning of the supply pipe after the boiler
Return temps are 130-140 when measured right before the pump

It seems that sealing up a small section of fins in the master is the easiset solution. I am just wondering if the correct amount of baseboard was installed. If we have another baby then I think i will need to more baseboard to that one room

 

[Jadnashua]

Are there any balancing valves anywhere in the system?

Fin tube heats by both convection of the air moving by, and radiation. YOu can cut down some of the heat transfer by either decreasing the flow, or blocking the convection.

 

[Dana]

Is it possible that the Taco pump is not powerful enough for the 2nd floor? I could swap the Armstrong pump back in and turn the speed up if that would fix the problem.

The pump doesn't have to raise the water-it only moves it. If the difference between the entering and exiting water on the zone loop is more than 25F there may be an argument for more pump, otherwise not.

Any ideas?

1st Bedroom - 111 ft2 / 892 ft3 - 4' of baseboard
2nd Bedroom - 148 ft2 / 1184 ft3 - 8' of baseboard
3rd Bedroom - 156 ft2 / 1251 ft3 - 8' of baseboard
(Master) 4th Bedroom - 275 ft2 / 2200 ft3 - 14' of baseboard

Start with a room by room heat load calculation. CoolCalc.com or LoadCalc.net are good enough. If the ratio of room load to baseboard length is all pretty much the same the room temperatures shouldn't be too far apart. It's the ratio that matters. If there is less load per foot for the master bedroom compared to the rooms on the zones, the other rooms will run cooler, guaranteed.

The heat load is not a function of the square feet of floor area- it's all about the areas of exterior walls and floors/ceilings with unheated (attic, basement) on the other side. Windows & doors have a much higher load per square foot than insulated wall assemblies, so that has to be all separated out for your load tool calculators to deliver reasonably accurate numbers.

If the room load per linear foot of baseboard ratios are all pretty similar, it's possible (likely) that the colder rooms are experiencing more outdoor air infiltration than others, or have gaps in the insulation. Gross leakage & insulation gaps can be fairly easy to figure out with an infra-red camera, but is also possible by other tools & methods. A pistol-grip IR thermometer can do most of what an IR camera does, but it takes more time. (A $200 FLIR for your cell phone can safe a lot of time, if you're a gadget person.)

Fixing the deficiencies of the building envelope is usually the first step in achieving comfort and balanced room temperatures (not screwing around with baseboards), starting with air sealing. Don't worry- you won't be able to make it "too tight" until about the third round of blower door and IR imaging directed air sealing, and then only if you're pretty good at it. Only when the house is tight enough is it worth making major hacks on the HVAC, (unless the ratios are truly all over the place.) The house & HVAC have to work together, and the house is (by far) the first & most important thing to get right.

Take a peek at some of short videos Nate Adams' "House Whisperer" site. While his examples usually are about hot air furnaces, the house charcateristics stuff is really spot-on:

Home Comfort 101

HVAC 101

You can spend a lot of time & money on the HVAC and never really get there if the house issues aren't dealt with first.

 

[Fitter30]

Your 30* difference in water temp is still within design. Ask your electric company if they offer a energy audit with a blower door test that will tell u how tight the house is. Insulation, windows and doors don't cost it pays every month. Pay me now or forever!

 

[Dana]

BTW: If the load per foot of baseboard numbers are coming in under 400BTU per foot part of the problem could be the high operating temp. When the water temp is too high the calls for heat are short in duration, not long enough to let temperatures in the downstream rooms stabilize before the thermostat is satisfied. If the high-limit were 160-170F the pump would run longer, and the duty cycle would improve, keeping the temperature swings within the rooms smaller. At the cooler boiler temp the temperature difference between the supply & return water on the zones would also shrink to something like 20F, which would also make the room temperature differences smaller.