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Crown boiler doesnt keep up with thermostat

Hello People,

I need help.  I have a 2flat building which is heated by a Crown gas boiler, 4 years old. In the second floor there are 5 radiators and on the first floor there were only 2.

During the first polar vortex at the beginning of January, the temp in the apartment dropped to 50 degrees. I called a company, they came out, told me I needed to add at least one more radiator on the first floor. It got done, but it didn't make a difference. Once the temp dropped below zero the boiler wouldn't keep up with the thermostat.

So I thought it might be an issue with the thermostat itself, which is a battery operated. Went out got a reasonably priced since there are only two cables coming out of the wall. I do not have a/c.

Here are some notes to add, I seen the water pressure go from 345 in the beginning of January and now its at 475. There is some type of measuring thing its always at 0. and the auto ignition pilot is making a funny noise. Now, the first guy that came said the noise is normal but I don't remember it making any type of noise during the previous years. I doubt this is enough information so please ask ask ask plenty of questions!!!


  • icesailoricesailor Posts: 7,265
    Water Pressure:

    "" I seen the water pressure go from 345 in the beginning of January and now its at 475.""

    I don't know where you got those pressure figures from but if they are true, it should be blowing the faucets off the wall and the water heater pressure relief valves should be spewing all over the place. Unless someone plugged the relief outlets.

    If your heating system (Crown Boiler) is reading any of the above numbers (354# to 475#), it couldn't have a 30# pressure relief valve on it because it would be a steady torrent. Or the relief valve is missing or it is plugged to stop the leak.

    Without a personal "Look-See", it sounds like the 4 YO New Crown Boiler is undersized for the application. If a additional radiator didn't change anything, that isn't the problem.

    Was a complete and accurate heat loss done on the building by the installer or did the lowest bidder tell you that the boiler he was proposing to install was more than big enough? It sounds like it isn't.

    Easiest way to know is to use the Short Bus methodology.

    If it is 40 degrees outside, turn on the thermostat to 70 degrees. Does the room get close  or to 70 degrees? The boiler is OK for 40 degrees outside. When the outside temperature is 20 degrees or lower, will it still go to 70 degrees? If it doesn't and the boiler doesn't shut off, the boiler is too small. If the boiler shuts off but the rooms don't heat to 70 degrees, there's not enough radiation.

    Is there a lot of un-insulated big pipes in unconditioned spaces like basements and crawl spaces? If so, insulate the pipes.
  • SWEISWEI Posts: 7,356
    It's also possible

    you have a pumping problem (assuming this is a hot water system and not steam.)  When it's cold enough outside that the boiler "can't keep up" does the boiler run continuously, or does it cycle on and off?
  • Crown boiler doesnt keep up with thermostat

    I can post a picture of the blue box where I got the numbers from, I asked the last guy that looked at it and he told it was the water pressure box. Also get the correct model name or number.

    And to answer the other person's question this system is steam, not water. I know that because of the radiator I recently purchased.
  • vaporvacvaporvac Posts: 1,512
    Post to Strictly Steam...

    You might get more replies if this is truly a steam system. I am a homeowner like yourself with a steam system, but have NO idea to what those two numbers refer. Maybe it's digital read-out of the pressuretrol settings? Definitely post some pictures. The zero , I suspect, refers to the pressure in the boiler...It's good to have low pressure, but it usually goes up when trying to make steam in design conditions (ie. very cold weather), so something is amiss. Are the pipes insulated?

    You might measure ALL the radiation (see this post for info: OR They numbers may not be precisely correct, but it will get you a ball park figure to compare to the BTUs of the boiler. Try doing that and then post those and the specs of the boiler ie BTU, model # in Strictly Steam rather than Gas.

    Hope that helps a little.

    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • Crown boiler doesnt keep up with thermostat

    It's a steam system.
  • Crown boiler doesnt keep up with thermostat

    The blue box is labeled Programmable Water Feeder. According to what you are saying, the unit may be too small. It does reach correct temp when weather is above 20 degrees outside. Once it dropped it doesn't work correctly, as I mention before. It doesn't turn on/off - it does stay on but radiator stay luke warm. Working on pics and specs.
  • vaporvacvaporvac Posts: 1,512
    Measure rads...

    The only way of knowing if it is correctly sized is to measure your radiators and compare that to your boiler size. I only have a manual water feed so I don't know what those numbers mean. Thanks for clarifying.

    Adding that radiator may have just made things worse if your boiler had a hard time keeping up before. However, there may be some other things that contribute such as uninsulated piping. The experts in the Strictly Steam section can help you figure it all out once you get those numbers and the pics. They really know their stuff! They helped me!
    Two-pipe Trane vaporvacuum system; 1466 edr
    Twinned, staged Slantfin TR50s piped into 4" header with Riello G400 burners; 240K lead, 200K lag Btus. Controlled by Taco Relay and Honeywell RTH6580WF
  • Crown boiler doesnt keep up with thermostat

    Crown - BSI207ENPZZPSU - 207,000 BTU - Gas-Fired Steam Boiler - Natural Gas - 82.3% AFUE - Chimney Vented

    Low Water Cut Off Type                                                         Probe Product LineBermuda MediumSteam Fuel SourceNatural Gas Combustion TypeConventional Vent TypeChimney Vent DHW ProductionNo Mount TypeFloor Maximum Altitude (Feet)2,000 Assembly TypePackaged ConvertibleNot Convertible Performance DataMaximum Input Capacity (BTU)207,000 DOE Heating Capacity (BTU)171,000 Net I=B=R Capacity (BTU)128,000 Efficiency (%)82.1 Efficiency TypeAFUE   
  • Bonnie_rBonnie_r Posts: 9
    edited February 2014
    Crown boiler doesnt keep up with thermostat

    Sounds like I'm on the wrong thread, thank you!!

    I will repost
  • ChrisChris Posts: 3,056
    A Steam System

    A boiler is not sized by Btu/hr in a steam system. It is sized by the sqft of EDR (Radiation) and the boiler chosen for the job needs to be able to produce that sqft of EDR. My suggestion is to start measuring radiators before you do anything else.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • BobCBobC Posts: 4,336
    More info needed

    Your boiler was feeding 7 radiators and now it's firing 8; unless those radiators are absolutely huge I can't believe your boiler is sized too small. Just to be sure measure each radiator and post the info here and we can approximate the EDR of the system. We will need to know the following for each radiator -

    Height from the floor up to the top

    Width of the radiator and the number of sections

    Depth of the radiator and the number of columns per section

    Type of air valve on each radiator

    Number of pipes feeding the radiator.

    It is possible the boiler is not firing at the rate it should be, somebody should clock the gas meter to be sure it's getting the right amount of gas. Also are there any signs of leaks in the piping, radiators, or boiler?

    Beyond that your piping might need work, if it's not piped right it will never work right. Post some pictures of the boiler from different angles and the piping around it, also post a picture of a representative radiator (both ends).

    My steam system is feeding 7 radiators and the boiler rating is half the size of yours (105,000 BTU and 287 sq ft of steam), my radiators total up to 210 sq ft of EDR and it heats the house just fine.

     With the above information we should be able to help you.
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
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