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

Radiant Hydronic baseboard sys keeps bursting. - seeking guidance

zarkbuilder Member Posts: 1
edited February 16 in Radiant Heating
Hello Experts,
We're a bit frustrated as the radiant hydronic baseboard system has burst (freezing pipes) for the third winter in a row. interior house damage this time is significant (ugh). details below. Seeking guidance on several levels:

a) how to determine that a licensed plumber is knowledgeable in radiant?
(I will reach out to an advertiser who is more than an hour from my location, but incase I am too far.......)
b) what DIY items can I look at now to bandaid the situation?
c) what should I/plumber do next season to avoid bursting pipes?

background: Ohio Valley location. Solid brick two story house 90 years old. Exterior brick in excellent condition, plaster interior, no 'modern' insulation, windows are 20 y/o insulated type. After elder passed, house is lived in part-time. During Winter months, house can be empty for long periods.

System: Separate Radiant Hydronic baseboard systems were installed more than 15 years ago for each floor. Boilers are clean and look like they were installed yesterday. The open ceiling unfinished basement displays piping going everywhere. We labeled almost all the pipes/valves years ago to reduce confusion. When the systems work, whole house is very comfortable.

Symptoms: the Second floor has burst almost every the time, on the shady side of the house, the (absolute?) farthest point from the boiler source. The first burst, the plumber found a brick within the chimney had fallen into the exhaust(?)/flue of the boiler eventually shutting it down. Second burst, there was an unusual sudden significant drop in outside temp below 0F that lasted for many days. Plumbing Co. said they had hundreds of calls. OK, bad luck maybe.

Current Setup/problem: Third year in a row, burst occurs, but nothing appears unusual. We set both thermostats ('old' honeywell dials) to 70F while gone. In advance of a temp drop, we increased the thermostats to 80F. Outside low touched 10F for two nights, then low was in the 20Fs. Day time in the 30Fs. Never lower this winter. Neighbors say no power failure. We asked neighbors to lower thermostats back to 70F, massive second floor flooding discovered. #$%&. These low temps were not that cold. It is a HEATING system after all. .....And, I'm not in the Yukon. I insulated all the hot copper pipes in the basement ceiling upto the point they elbow upstairs. I find it curious that the bursts occur in the highest area in the house where heats rise, but contradicting this is the area is the furthest from the boiler.

Plumber: We have been using the same large plumbing company that has about 15 trucks and does primarily residential work in our and surrounding areas. Yes, they know radiant heat. or maybe they dont. the repair work is expensive, but some of the older guys know the older systems and know how to get the parts. They have repaired and checked the system numerous times in the past three years. One problem is they send different guys to our house. Sometimes for the same repair. Pro fixes a problem, but no knowledge acquired by them about my house and none shared with me. My faith in them is lost. I learned very recently that anti-freeze may be able to be added to a radiant system. They never told me that.

I am DIY capable. I have a Plumbers wrench, I have a pipe cutter, I do not want to weld (thats for the pros), I can test some electric circuits with a ohm meter, I've installed my own house toilets (after the original plumber did not level them correctly years earlier). So I can figure out stuff, but I do not pretend to be a Plumber.

In addition to my Questions a,b,c above, I have some other not-brilliant questions that I am hoping I can get some guidance on:
-If anti-freeze can be added, where? I do not see any obvious inlets.
-Can the whole system be drained? We have a drain for the cold running water in the house (sink, bath, etc.), but not any other pipes as far as I can tell. it is a maze.
-Water leak alert systems. more than 5 years ago, i looked into this, but they were considered very inaccurate (moisture conditions create false alarms). Some monitor water usage, others monitor for flooding. Any suggestions for stand alone flood alarm OR complete systems (that are part of a house security system)?
-below freezing temps are almost over. Placing an electric heater in the basement and turning both radiant systems off for a few months. Pros/Cons?
-I have a laser thermometer. What temp should it read on the hot pipe surfaces in different locations? Exiting boiler? 50 feet away in basement? first floor? second floor?
-What should the hot water RETURN pipe be before re-entering the boiler? I am sure distance is a factor.
-AFTER repairs (in the future) by a pro, how do I confirm there is no air in the system?
-Can setting the thermostat too HIGH, be a problem?
-What are the common reasons for radiant pipes bursting that you have seen?

I hope to locate a small plumbing outfit that knows radiant, will learn this old house, and teach us how to prevent future disasters.
Thank you for taking the time to read our issue. Your suggestions are appreciated.
Ark Building has begun.........


  • yellowdog
    yellowdog Member Posts: 157
    The first thing to do is to find the split pipe that caused all the flooding. Now look in that immediate area to see why that pipe burst in that specific location. Then fix the reason the pipe burst. It could be a pipe run too close to an outside wall. There could be a pipe that is no longer covered by insulation in the attic. Step one is to find the source of the water.
  • psb75
    psb75 Member Posts: 833
    You need to thoroughly inspect the places where the plumbing froze and split--present AND past. Look for patterns of "why here--specifically?" Given your history and description of the building and how it is operated, glycol is highly recommended. Yes there are several places to fill the system. Yes you can drain any system. Glycol is expensive and is hard on system components. It is a necessary "band-aid." You should also have a way to carefully monitor the interior temperatures remotely in order to catch the problem EARLY. There are systems that send emails and phone calls to you and service people.
  • GGross
    GGross Member Posts: 1,043
    edited February 16
    Pipes burst generally due to freezing. If your boiler locks out and can't heat the water, and you are not there for enough time that sections of the pipe freeze, they will burst. I recommend some glycol for anyone who is not going to be in the building for a length of time during winter. If your heating system pipes are bursting a wifi thermostat, or any way to monitor the house temperature remotely is an incredibly easy way to prevent this, once the temperature inside starts to drop you know the boiler isn't working and could call someone to repair it before a pipe bursts, glycol should still be used, but you likely don't need that heavy of a concentration . I am shocked that after 3 bursts not a single pro suggested either of these simple investments, I am even more surprised your insurance company hasn't required these things to be done to prevent future payouts. If you have pipes running near outside walls, providing better insulation on those walls will add to the time it will take for your system to freeze. It usually takes quite some time for bursting to occur if you were to have even a weak concentration of glycol.

    Water leak systems are nice to put under fixtures etc. If your heating pipe bursts though it is almost certainly due to freezing, and once the leak detector goes off the damage is already done. I'm not saying you shouldn't install one, just don't let it be the only thing protecting you.

    If your boiler has an automatic fill valve installed, you should really figure out if your system has leaks and really needs an autofill.. If its leaking its not a great one to leave without someone to look after it. When your pipe bursts, it may be frozen at first, but eventually that will melt and once it does the fill valve will continue adding water to the system that will just come out the burst location adding to damage
  • Jamie Hall
    Jamie Hall Member Posts: 23,276
    I'm quite sure there is a way -- though it may be a bit tricky -- to add glycol to your system. To figure out how, a few pictures in the vicinity of the boiler would help.

    And yes, I know glycol is a nuisance. So, however, are frozen pipes...

    Now the two suggestions above mine here are good, but there's more. A baseboard system should circulate at least once -- preferably twice -- every hour. How long it needs to circulate depends on how much heat is needed, of course, but it should. This depends on the thermostats. The old Honeywell dials should do that -- but it may help, oddly, to lower the water temperature going to the baseboards from the boilers, so they would have to run longer to keep the house warm. How low? Now that's a bit of a guessing game, but when the temperature is at, say, 20 in your area I'd want them running about half the time at least.

    What is the make and model of your boilers? It's probable, given the age, that they aren't condensing -- so the lowest return temperature they should see is around 140. This may mean that you need to use what is called "primary/secondary" plumbing, in which there is a loop which circulates through the boilers, and a different loop which circulates through the heating. That second loop uses a mixing valve to take some of the return water from the radiators and mix it with the supply from the boiler to get the temperature of water in the radiators where you want it.

    And the last comment I'll have right now is to make sure that the air is out of the system so it can circulate, and that the system pressure is adequate. You want, for the second floor, about 15 psi as a minimum. Again some pictures will help here.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Ironman
    Ironman Member Posts: 7,375
    The most common cause of heating pipes freezing and bursting is that they’re run through an unheated space and not insulated. Add to that the fact that you have two zones and heat rises from the lower floor to the upper which keeps that thermostat satisfied, and the water in the pipes isn’t flowing for extended periods, and you have the cause of the failure.

    Glycol would be a good choice in your situation, but it has to be mixed to the proper percentage (about 35%) and checked with a refractometer. It also has to be pumped in. It’s not a DIY project.

    Also, insulating the pipes in any unconditioned areas and leaving the upper thermostat set about 5-10* higher than the lower one.

    Turning the thermostats down and putting electric heaters in the basement is the worst possible thing that you could do.

    Also, draining the system for the winter is not a good idea as water will lay in any pipes that are not sloped back towards the boiler and the freeze and break.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • psb75
    psb75 Member Posts: 833
    Jaime is advocating that you should "get the air out." Boiler system water should be greatly "deprived" of oxygen--and it is like all heated water--less dense. Unfortunately, it is more "prepared" to freeze! "Heat" keeps it from freezing and so does "movement." You can change this "ready and waiting to freeze" scenario by ADDING GLYCOL to change the nature of the the boiler system fluid. You must maintain a certain percentage of glycol in the system. You must monitor the PH of the system. Glycol is not as effective at transferring heat and it is not as easy for the circulators to circulate as "plain" water. It is not as easy to remove air bubbles from it. There are quite a few trade-offs with glycol. I'm not a big fan of the stuff. You can tell.
  • hot_rod
    hot_rod Member Posts: 22,120
    A brick house with no insulation will be tough on exterior wall baseboard. The heaters on interior wall may have been a better choice.
    Glycol is your best option, both for current problems and also extended power outages.

    The system should be cleaned and flushed first. You can buy cleaners that squirt into the boiler from an aerosol can.

    Assuming the system is leak free, add a 40% propylene based hydronic glycol. You will need to check the fluid every few years, test kits or strips can be used for that.

    If the baseboards are aluminum, use a multi metal glycol. Rhomar is a good brand for cleaners and glycols.

    A small pump to put the glycol in. Even a small plastic sump pump from a hardware store will work.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Intplm.
    Intplm. Member Posts: 1,945
    Keeping the heat on and circulating through the zone(s) of your system and adding glycol to the system will lesson the chance of freeze ups/burst pipes.
    Adding glycol that is made for a domestic hot water heating system is what you want, and not what is used in your car.

    Also as a precaution, adding proper insulation to any suspected problem area is also a good step, but pipe insulation and building insulation are two different animals.
    Did you insulate around the pipes with insulation that is house insulation? leaving enough room around the insulation so that it will trap air and therefore work properly or is it stuffed and crushed? Did you only use pipe insulation fitted to and on the pipes? Are the pipes that are bursting installed near an eave or other singular cold area? I suspect that they are, as cold air has a funny way of finding pipes.

    As to adding glycol and purging the system? There should be a purge set up at each zone hopefully on the return piping of your boiler. This is a common place for removing water and adding glycol. Adding water to the boiler is also going to be in a similar location.

    Pictures of your boiler and boiler piping near and around the boiler at different angles posted here would help.
  • Daveinscranton
    Daveinscranton Member Posts: 148
    Agree with the above.

    You could add a timer to flip on when away etc.   Idea being 2-3 minutes of water circulation every 15 minutes regardless of heat call.  Not hard.  (Famous last words).

    Getting to the root of the problem and solving it is better.

  • Jamie Hall
    Jamie Hall Member Posts: 23,276
    psb75 said:

    Jaime is advocating that you should "get the air out." Boiler system water should be greatly "deprived" of oxygen--and it is like all heated water--less dense. Unfortunately, it is more "prepared" to freeze! "Heat" keeps it from freezing and so does "movement." You can change this "ready and waiting to freeze" scenario by ADDING GLYCOL to change the nature of the the boiler system fluid. You must maintain a certain percentage of glycol in the system. You must monitor the PH of the system. Glycol is not as effective at transferring heat and it is not as easy for the circulators to circulate as "plain" water. It is not as easy to remove air bubbles from it. There are quite a few trade-offs with glycol. I'm not a big fan of the stuff. You can tell.

    By "get the air out", @psb75 , I meant -- as should have been obvious, but perhaps not, to make sure the system is thoroughly purged. Nothing like an air lock to slow circulation. The notion that hot water is more prepared to freeze than some other water is, to be blunt, pure nonsense.

    A good air removal device will keep the air out of a glycol system quite effectively. That is not a problem, unless there are leaks and you are adding water to the system regularly.

    I agree that glycol in a system makes it hard to work on. It also has slightly reduced heat capacity than pure water, and slightly reduced heat transfer characteristics. It also, however, reduces the freezing point of the solution -- properly mixed, to around -30 or lower. This is the objective of the exercise (in liquid cooled engines, both that and the fact that it rasises the boiling point are advantages).

    All that said, if one is dealing with a heating system in a house in an area which can get below freezing, you have four choices: either you put antifreeze (glycol) in the system, or you have a reliable person check the house every single day when the temperature is below freezing, or you drain the system for the winter, or you pay for the water damage when a pipe freezes. Take your pick.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England