Old Houwe W/ steam heating problems

cos

I have a old two pipe steam heating system.  I can not get heat out of two radiators, no steam pressure on the gauge sight glass is 1/2 full and the furnace has been flushed out. I have put back two radiators in the system that the previous owners had taken out ,replaced  all the non working steam traps  If I open the  valve (open the supply side of the fitting ) at the radiators in question  the pipe will get hot.and if I take the top off the trap the water will eventually come out and heat the radiators up .What could be the problem  or problems,?

Dave in QCA

Traps can be tricky

One thing to remember about steam traps in residential 2-pipe very low pressure / vapor systems, the traps act as vents, and they will not vent if there is an obstruction.  If your piping creates a pool of water, it will not allow the air to pass, and so the radiator won't heat.  Speaking from experience, I replaced a side outlet trap with a regular angle trap with the outlet on the bottom.  I inadvertantly changed the angle of the piping leaving the trap, created a puddle of water in the pipe, and the radiator would not heat.

Other things to remember in these vapor systems is that different models and makes of traps have different size passages and thus, they vent at different rates.  It is best to keep the traps the same, or at least with similar venting capacities.

What type of traps do you have?  Could you take some pictures of the radiators that won't heat, as well as those that do.  Make sure you get shots of the piping at the inlet and outlet.

Jamie Hall

Several things...

First, the sight glass being half full is, usually, just about right.  Some boilers run a little higher, some a little lower; if you have the installation instructions for your boiler, it should say in there somewhere.  Otherwise, post the make and model number and someone may have the information.



Second, not developing visible (on the 0-30 psi code required gauge) is also normal, except towards the end of a very long (half hour to an hour) run.  You don't mention whether you have a pressuretrol or a vapourstat, or what they are set to, or whether the boiler cycles off on pressure towards the end of a long run.  That would be helpful information for our trouble shooting.



Third, on the two cold radiators.  There are two possibilities: the traps could be failed closed.  This isn't all that uncommon, particularly on systems which haven't been particularly maintained or which have been run on excessively high (over 2 psi) pressures.  One can get replacement innards for almost any trap ever made, so that shouldn't be a problem if it is the case.  The other possibility is that something may be blocking the return pipe.  It could be as simple as being pitched incorrectly, allowing water to accumulate in it.  It could be that someone disconnected it and capped it when the radiator was removed; I've seen that.  I've also seen a situation where someone had put a valve on the return pipe -- and closed it.  So check the return pipe all the way from the radiator to the main return.

World Plumber

open trap

You may have an open trap that is pressurizing the return blocking the venting of the others. Do you have a laser thermometer? Take the temperature before and after the working radiators. The post trap side should be considerably cooler. If you find one that is about the same. It's not closing. That will allow the return to fill with steam and the steam won't move through the others.



MC

cos

did a few things

First I drained the return line got about a 1/2 gal of hot water out of the return line( this line is connected to the steam line) then got a trickle of hot water with some steam went to the furnace drained water out of this trap got a gallon or so of cool water, went to one of the radiators in question pulled the new trap, a hoffman 17c ,cleaned checked for air flow through the openings seemed clear re attached and poened the shut off got some heat to the radiator .

disconnected the new valve on the other radiator and within a few seconds I had a very hot pipe with steam commimg out of the valve ,re connected shut off valve and then took the top of the hoffman 17c trap off and water was draining out of the trap down the pipe. radiator was heating up slow I was getting short of time so to speed the process up a little I shut some of the other radiators that were working off and got heat out of the two radiators in question. went back today to check on the questionable radiators and both were cold. Now just a point that might have something to do with the problem.When the house was purchsed the previous said that they dissconnected one radiator in an upstairs bed rm because the rm got to hot and was not needed

The one in the kitichen was removed for remodleing I reconnected the two radiators,the one upstairs works great (had new shut off and trap put on this one) the down stairs one is one that I am having the problem with it also has new shut off and trap on it Now could the system not handle the two added on radiators?I need help on this cause I am lost on how to fix it