Uneven or incomplete or insufficient heat deklivery 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.

Fix Insufficient or Uneven Heat

This article provides diagnosis and repair steps for hot water or mixed hot water & steam heat systems that are not giving enough heat or that are delivering heat unevenly in a building.

If your heating system is by forced warm air furnace, see NO HEAT - FURNACE which includes addressing insufficient warm air heat.

Article Contents

• BOILER NOT GIVING ENOUGH HEAT
• UNEVEN or NO HEAT in SOME BUILDING AREAS
• UNEVEN HEAT with MIXED HOT WATER / STEAM RADIATOR TYPES

Boiler Not Delivering Enough Heat

Our reader asked how to help solve a home that was not getting enough heat. The homeowner tried turing his aquastat HI limit to above 200°F - an unsafe idea that wouldn't work anyway.

House Not Warm Enough & Boiler relief valve spills if aquastat temperature is set too high

I work for a church, headed to a members home.

He said his heating boiler is shutting down on high limit. If he adjusts too high it opens the relief. Any suggestions where to start? - On 2017-01-12 by Doug

by (mod): Key diagnostic questions & answers when a heating boiler shutting down at high temperature

Doug:

If the boiler is reaching the HI limit set on its aquastat temperature control, that itself is unusual.

See AQUASTAT HI LO DIFF SETTINGS to see how the control works and how it should be set .

Watch out: pushing the boiler temperature higher than 200°F or trying to do so is unsafe. And if the homeowner is doing that because they are not getting enough heat, that approach is wrong and the problem lies elsewhere.

Watch out: if you are not trained in heating system repair, and because at least some of these conditions are dangerous, unless you see something trivial and obvious such as windows open, you need to bring a trained heating service technician to the home.

Usually if a residential boiler temperature exceeds 200°F OR boiler pressure gets ove 30 psi, the pressure relief valve will spill (RELIEF VALVE LEAKS), dumping hot (scalding) water to preven the boiler from blowing up (a BLEVE EXPLOSION).

So if the boiler is shutting down, some other safety control must be detecting a problem. OR there is another safety control involved.

Virtually ALL of those conditions involve some direct or indirect safety concern.

On site I'd expect an experienced boiler service technician to be considering a couple of lines of investigation:

1. What control is actually turning the boiler off?
   
   That itself is diagnostic and will point to an operating or control setting problem.
2. Why is not enough heat being delivered into the home?
   
   That, too may point to a boiler problem that could be as simple as the boiler is long past due for cleaning (poor heat transfer into the heating water), or something a bit more work but not hard to understsand, such the examples I'll give below.
   
   For each example I'll give a starting point for reading up on diagnosis and repair for that item.

When not enough heat is being delivered to the home, and assuming you can at least confirm that indeed they have hot water heat (hydronic heat) such as from hot water baseboards, radiators, or convectors, then provided the aquastat is set properly, the problem is elsewhere such as

• The room thermostat is not responding properly to actual room temprature
  
  See THERMOSTATS, HEATING / COOLING - home
  
  and THERMOSTAT CALIBRATION 
• The aquastat's temperature probe sensor isn't working correctly or has poor thermal contact with the boiler water or sensor well
  
  See AQUASTAT SENSOR PROBE HEAT CONDUCTING COMPOUND - I don't think this is your case
• A circulator pump isn't running - heat is delivered too slowly, working just by "gravity" or convection
  
  See WEAK HEAT, WEAK CIRCULATOR, TOO COOL 
  
  and CIRCULATOR DIAGNOSTICS
• A zone valve isn't opening
  
  See ZONE VALVES, HEATING - home
• The heating water circulating system is partly airbound
  
  See AIRBOUND HEAT SYSTEM REPAIR 
• The home is poorly insulated or has a lot of drafts and air leaks -
  
  See AIR LEAK SEALING STRATEGIES - home
  
  and HEAT LOSS in BUILDINGS - home
• Some other heating boiler problem is limiting heat delivery
  
  See DIAGNOSE & FIX HEATING PROBLEMS-BOILER 
  
  See UNEVEN or INSUFFICIENT HEAT DIAGNOSIS

...

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.
  
  The result can be some rooms or heating zones or even just part of some heating zones get no heat or get only reduced heat.
  
  
  • See AIR-BOUND HEATING SYSTEMS - home
• 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

...

Solving Uneven Heat: Mixed Radiators & Baseboard Heat

Uneven Heat at mixed hot water or steam combination 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.

...

 

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Opinon: Reader believes boilers don't make enough heat during the heating cycle

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) (Jan 24, 2012) scott

 

Need suggestions for better heat control

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. (Apr 3, 2012) Jessie.

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.

 

We have insufficient heat from radiators in some rooms

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. (Jan 27, 2013) ralph

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;

Take a look at the diagnostic at

AIRBOUND HEAT SYSTEM REPAIR by WATER FEED VALVE

 

Heating baseboard wont' shut off regardless of thermostat setting

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! (Apr 12, 2014) Wayne

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

THERMOSTAT WON'T TURN OFF

and the diagnostics and repairs

at HEAT WON'T TURN OFF

...

Continue reading at RADIATORS for ROOM HEAT or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• AIRBOUND HEAT SYSTEM REPAIR
• AQUASTAT CONTROLS - home
• COLD HEATING RADIATOR REPAIR (hot water / hydronic heat)
• NO HEAT - BOILER - if your heat is by forced or gravity hot water or steam

• NO HEAT - FURNACE - if your heat is by forced warm air

Suggested citation for this web page

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

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING SYSTEMS

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