Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Diagnostic Challenge: Time for a New Boiler?

I own a 50-year old house with a 50-year old Burnham boiler. Two-zone heat: one up, one down. The downstairs loops have three pipes (not runs) under the slab.

For at least the past five years (since we owned the house) we've had 'brownish' water from the boiler (when drained). I always thought this was rust, but a friend of mine said no, it was actually mud (!) and evidence that the three underground pipe runs have been compromised.

Symptoms: Boiler demands water constantly and has LOTs of air noises. Pressure rarely stays above 15. Heat valves (Taco) are balky; on cold days I have to jam the valve into manual to get heat to the upstairs zone. (If the soil-incursion theory is correct, I suspect there's a bunch of mud/debris sticking in the valve.)

The options to fix this:

1) Create two zones from the downstairs one zone, repipe with PEX and do returns above ground. The replace the valves and pump (since they're likely corroded).

2) Same as above, but get a new boiler. I would really prfer not to due to the cost.

3) Try Fernox Leak Sealant. My plumber is not a fan, but I have seen some posts about the product and it looks intiguing.

4) Try some sort of in-situ repair, like a ePipe. Again, thumbs down from my plumber. I am worried that the thick layer of epoxy throughout the entire system will a) not work and b) cause system-wide inefficiencies that will make the boiler work even harder to produce heat.

I'll monitor this post if anyone has any further diagostic questions. And I'll post any photos that you may need to further your diagnosis.

Un-happy Homeowner


  • Zman
    Zman Member Posts: 6,989

    I think you would reap huge benefits by replacing your boiler. The energy saving would likely be 20-40%.

    No matter what,  you need to fix the leak. Are you able to isolate the zones and tell which is losing pressure? What type of piping do you have?

    I don't think I am buying the mud intrusion theory. If you stick a hose in the mud and turn it on, does mud go into the hose? When you lose water in a closed system, the water is replaced with oxygenated water. This oxygenated water rusts your boiler.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Gordan
    Gordan Member Posts: 891
    If this has copper tubing embedded in concrete

    then there's a good degree of likelihood that this is what's leaking. The fly ash in the concrete mix has been a known culprit, eating away at copper pipe over the decades. If that's the case, fixing leaks may only be a temporary solution as new ones are likely to develop. Whatever the case, the leak is more than likely the direct or indirect cause to all of the symptoms you're describing, so take Zman's advice and try to isolate in which circuit it is located and deal with that (or have a plan for dealing with it) prior to any other system changes.
  • pipeking
    pipeking Member Posts: 252
    good idea!

      zman got a good point, if there r 3 loops of radiant isolate each loop and give yourself purgeing isolaters on the supply and return of each loop and flush them with clean water to find which 1 is the culprite.

    i would sugjest replacing the boiler if it is that old, any 3 pass oil fired boiler would pay for itself in no time, really. a 3 pass boiler compared to the one u have now could have up40% more efficientcy! an easy way i tell customers on how effientcy works in a boiler is to tell them stack temps. your boiler now prolly put 525*f-650*f+ up the chimney, a 3 pass boiler, i like the (burnham mpo), can get into the 300*f+ range
  • Test Methods: Leak vs. Corrosion

    Thanks everyone for thoughtful, speedy replies.

    1) Is there some sort of definitive test to determine if the boiler water discoloration is from corrosion or soil incursion? Based on the discussion, this seems to be a key fact before we decide on a fix strategy.

    2) I've attached some additional photos for your consideration


    a) the water has small particulates that sink in the glass within two-three minutes.

    b) I left the feed water running all night (to fix th 'gurgling' sounds of low water in the pipes). The pressure relieve valve "blew" over night, so I think we've hit the fill line.

    c) pressure gauge is at 20.

    I'm pretty sure we'll need a new boiler so at this point I just want to know (definitiely) if this is a leak that needs a PEX bypass, or whether this is SOLELY a decaying boiler.
  • Zman
    Zman Member Posts: 6,989
    How long..

    How long does it take to lose pressure? I take it you don't have an automatic fill valve with prv?

    Does the debris in your glass stick to a magnet? Does it look scaly or granular?

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • reply

    I taped a magnet to the side of the glass and, as you can see from the photo, *some* but not all the sidement stuck.

    I also filtered the glass' contents through a coffee filter, and examined them under zoom, Video.

    Boiler liquid is relatively clear...not the muddy stuff as before.

    Boiler pressure has dropped (now around 15) since six housr ago.
  • Zman
    Zman Member Posts: 6,989

    link doesn't work
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • OverTaxed_Homeowner
    OverTaxed_Homeowner Member Posts: 8
    edited January 2013
    Link (to video) showing magnetized residue filtered from boiler water discharge
  • Gordy
    Gordy Member Posts: 9,514
    Magnet test

    Take a magnet to the sediment in the glass. If its ferrous metal it should be attracted to the magnet. This will rule out the mud theory, but obviously you still have a leak somewhere.

    Agree with zman, and others if possible isolate loops, and pressure test each one. Maybe only one has a leak.

    The leak could be attributed to concrete settling, and cracking a tube. I have copper tubes in concrete for over 60 years with no troubles,but as Gordan said if the concrete was a high ratio of flash then it is the culprit.
  • reply

    Yes, I think a pressure test is the next step.

    Facts in favor of NO repipe (i.e., boiler is decaying but no pipe leaks):

    - sediment is magnetic (rust) or grey colored

    - water (when drained) is not 'muddy'

    - heat is still functional

    Facts in favor of PEX repipe/bypass (i.e., leaky underground pipes):

    - pressure declines over six hour period

    - constant water gugling noise

    - water feed is running all the time (never satisfied)
  • Zman
    Zman Member Posts: 6,989

    You don't by chance have access to an IR camera? In some areas you can rent them. If you run the heat on high for a while the leak should look like a blob on the image.

    Losing 5 lbs in 6 hours is not a huge leak. You may just have one pinhole. They tend to form where the pipe penetrates the slab if it is corrosion from the outside. If it is due to pipe wear it will usually be after a 90.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • icesailor
    icesailor Member Posts: 7,265
    FHW Water Boiler:

    Isn't that a Forced Hot Water (FHW) boiler and not a steam boiler? Why are there pipes buried under the floor?

    Did I miss something? (Probably)
  • Gordy
    Gordy Member Posts: 9,514
    edited January 2013

    " the downstairs loops have three pipes not runs " Not sure if these are radiant loops in concrete, or supply/return pipes for convectors.
  • pipe runs

    The house is a bi-level/raised ranch. The heater is forced hot water (not steam) with bnaseboard radiators. The downstairs zone runs the perimeter of the house.

    In three sections the water pipes run under (or through) the slab.

    Two sections are 12' long; the third is about 25' long.
  • Gordy
    Gordy Member Posts: 9,514
    edited January 2013

    I have the same set up in my rental which is on a slab. Lost one loop with three baseboards where the pipe came out of the slab to the first one. Repiped above the slab. I should add it was on the exterior wall not to sure it could have froze, and broke.
  • IR Camera

    No, I don't have access to an IR camera, If the leak is under the slab, will it be visible inside the home (under carpet) or flooring?

    This bring up two questions:

    1. Should I hire a 'leak detection' company (which may have access to spealized gear)?

    2. Should I stop when I find *A* leak, or should I find the exact location of the leak?

    I've been told that *ANY* leak means that the entire underslab pipe runs are likely no good. So, even if it is a pin hole, then a single leak only presages multiple leaks down the road.

    At this poing I'm trying to figure out if there even is a leak.
  • Repipe in Rental

    What was the cost? Can you provide a bit more details?
  • Zman
    Zman Member Posts: 6,989

    Do your underslab loops have isolation valves? If not it may be worth cutting some in.

    If you isolate a loop and you stop loosing pressure you have found your leak. If you replace with pex, you could probably run it in 1/2" and cap it with oversized baseboard.Doors are a challenge.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Gordy
    Gordy Member Posts: 9,514
    edited January 2013

    Cost was low, but it was an easy job. About 60' of 3/4" copper some fittings, and drill some holes through partition walls. The boiler room was in close proximity. There was three baseboards in series about 24' total. The supply to the second baseboard was the culprit.

    We do not discuss pricing.
This discussion has been closed.