Uneven or incomplete heat diagnosis & repair for buildings: this article describes the diagnosis & repair of cold heating baseboards, convectors, radiators, or steam radiators.

We provide articles that help in diagnosing and repairing no-heat problems with each types of hot water or steam or fan convector heat delivery systems.

We include a list of things to check if some building areas are not receiving heat or are receiving too little heat.

Explanations for Uneven Heat - Mixed Systems of Radiators & Baseboard Heat

Mixed hot water & steam combinastion heating systems

As Carson Dunlop Associates' sketch (left) shows, a mixed heating distribution system that combines cast iron radiators (or wall convector units) with heating baseboard in the same heat distribution piping loop can produce uneven performance.

The heating system's behavior will also be affected by the location of the thermostat. In our sketch, the heating control thermostat is located near the radiator.

Because cast iron radiators take longer to get hot in response to circulating hot water in the system than does finned-tubing baseboard, the room where the baseboard heat is installed will be very hot, maybe too hot, early in the heating cycle (while the radiator is heating up).

Then as the thermostat (located near the radiator) is satisfied and stops the boiler or circulator pump from sending hot water through the heat distribution piping, the hot, high-thermal mass cast iron radiator will continue to warm the room where it is located, while the room with the finned-tubing baseboard will cool off more rapidly.

The result may be that the room heated by the finned-tubing baseboard will be sometimes "too hot" and other times "too cold".

Advice for regulating steam heat to improve even heat delivery in a building is found at RADIATOR STEAM VENTS, 1-PIPE SYSTEMS.

List of Things to Check if Heat in the Building is Uneven or Incomplete with Some Areas Receiving little or no heat

Watch out If part of a building is getting heat and part is not, and the problem is not the radiator or baseboard itself, check these possible causes of uneven or partial heat distribution:

• Check for additional thermostats controlling different building areas and be sure the thermostat in the cold area is calling for heat and Check for an inoperative room thermostat in some areas (if more than one thermostat is in use in the building)
  • See THERMOSTATS, HEATING / COOLING
• Check for closed or partly closed radiator control valves or for a steam vent that is not working
  • See RADIATOR STEAM VENTS
  • See RADIATOR VALVES & HEAT CONTROLS
• Check for air bound heating radiators, baseboards or piping sections. If piping is hot leaving the heating boiler but heat is not reaching all radiating devices the system may be air bound.
  • See AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE
• Check for a circulator pump not working or a zone valve not opening in response to the thermostat
  • See CIRCULATOR PUMPS & RELAYS
  • See ZONE VALVES, HEATING
• Missing baseboard covers and damaged baseboard fins will reduce heat output from hot water baseboards or convector units
  • See BASEBOARD HEAT REPAIR - diagnose & repair
• Fan convector units will put out little heat if the fan is not working
  • See FAN COIL & FAN CONVECTOR HEATERS & HYDRONIC COILS
• Uneven radiant heat: check for improper tubing depth or location, or for sections of electric radiant heat not working or for multi-zone radiant heat, check zone balancing valves
  • See RADIANT HEAT FLOOR MISTAKES

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Opinon:

(Jan 24, 2012) scott said:
i can't help but comment after reading the article but in most cases the boiler is not able to produce enough heat in the beginning or during the heating cycle to cause the baseboard to give sufficient heat. baseboard needs a good 180 deg. to heat and as we know standing cast iron will give heat at any temperature. most (converted)gravity systems run much cooler (if they don't then you are really throwing a lot of money away and you have a lot more problems than this one)

Question: better heat control

(Apr 3, 2012) Jessie. said:
I have cast iron baseboards on my entire circut. I also have programable thermostats. The issue I have is at night... i have it set at 60... Why so low? because when the heat kicks on it runs and runs untill the air heats enough to trigger my thermostat to shut off. then for the next 30 min or so the room continues to heat... sometimes up to 70 degrees. I spend my whole night freezing and roasting. I need to configure a control system to kick on the heat for 5-10 min to heat up the baseboard and then let the carry over heat bring the room to a more even temp... I have looked for time stats but none of them will have it cycle on and off. I have looked at remote sensors... I think this may be my only option... any advice? I will save loads of fuel too since I won't be heating beyond my needs any more.

Reply:

I would look first at the properties of the building: look for air leaks, drafts, significant heat loss points

Second look at the thermostat location: it may be in a bad spot that doesn't accurately reflect the room temperature or that is affected by outside conditions, drafts in walls, even heat from the other side of a wall.

Question: insufficient heat in some rooms

(Jan 27, 2013) ralph said:
we have traditional radiators in the old part of our house and cast iron baseboards in our bedroom, which is an addition from before we bought the house 25 years ago. We get very even heat from the traditional radiators but insufficient heat in our bedroom. Don't know if it's simply a difference between the two types of heating or because the bedroom is farther from the boiler than any other room in the house. If I reduce the heat for the traditional radiators, but without changing the temp on the thermostat, will that allow more hot water to reach the bedroom? Any suggestions would be appreciated. Thank you.

Reply:

Look first for air-bound or partly air-bound heaters in the bedroom or piping to it.

Search InspectApedia for "air bound heating systems" to see details.

THen try drawing a sketch of the heating loop piping so that we can see where the cold bedroom is; let's see if the problem is a remote end of the heating loop bedroom;

Question: heating baseboard wont' shut off regardless of thermostat setting

(Apr 12, 2014) Wayne said:
My baseboard heating will not shut off regardless of the thermostat setting. My house is constantly 81 degrees. There is a switch on the side of my boiler that doesnt appear to be in the in the boiler manual.I tried flipping the switch, the boiler shut off. I dont know if it shut off because the switch controls boiler power or because the baseboard heating is shutting off and the boiler doesnt need to be on. I have a Weil McLain EG-50 boiler i believe, im not sure what the make of the baseboard heating is though. Please help!

Reply:

Wayne when heat won't shut off I check first for shorted thermostat wires. Try disconnecting the thermostat wires at the control end at the boiler.

See our article on this at

inspectapedia.com/heat/Thermostat_Stuck_On.htm

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UNEVEN HEAT DIAGNOSIS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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