Radiators not heeting

charlie_14

what if this still doesn't do it?
what else sould i try?

T.Ferns

Radiators not heating


I have been dealing with a problem for five or six weeks that I just cant seem to solve.

I have a customer where we installed a new Burnham Independence gas boiler (steam) in early December. The boiler seems to be operating just fine.

There are two problems. We installed a pretty simple, non-programmable, digital thermostat that the customer seems to be having difficulty with. We have explained the operation of ths t-stat to the customer several times and it doesn't seem to click. She is an educated and intelligent person and perhaps other (real) issues that we have there have clouded her confidence relative to the t-Stat.

The real problem here is that it is taking 90 minutes or so to bring here house up to temp in the a.m. She generally sets it back to @58 degrees at night and would like it about 68 degrees when she meets clients at her home office beginning about 8:30.

The home is not overly large and should, it seems, heat a bit quicker. Her feeling is that the home heated much quicker with the old boiler.

We, of course, calculated the sq. ft of radiation when sizing the unit. To be honest I seem to have made a math error. When we began investigating this I recalculated the load and it came out to 281 sq. ft., The boiler is rated at 271 sq. ft. close but not perfect. There is limited piping on this job and it is well insulated. There were no main vents on this job before we got there and we added one to each main. This is single pipe steam.

The reason the two main rooms are not heating is because the two large radiators in these rooms, 44sq. ft. and 60 sq. ft. are not heating all sections. We have changed the vents twice and even tested them with the vents out. They simply take an hour or more to heat past the eigth or ninth section. Each section that does not heat, we understand, is that many fewer BTU's into the room thus the slow time to satisfy the thermostat and thus the client.

It doesn't seem to be a pressuretrol problem either the boiler runs until the t-stat is satisfied without interuption from the pressure control.

I know the boiler capacity is closer than we would normally have speced it but with the 33% piping loss allowance built in to these boilers and the limited piping in this system I wouldn't think this would be a major issue. Still it is underperforming. The other six radiators (all smaller) in this house all heat well and quikly.

OUr client is away for a few days and I told her we would find a solution to this problem for her or have a knowledgeable second opinion performed on our dime. I have no heartburn with that or with replacing the boiler if that is what is required.

Help!

Thanks, Tim

John S.

balancing

could be the key here. If the other rads are heating well and a lot quicker, one possible solution would be to vent those radiators slower (shifting steam supply to the more difficult to heat radiators. Also, it may be worth while to check room temps after a normal cycle. Again, rooms that overheat can be 'slowed'. Could the vent on the radiator in the room with the t-stat be clogged? or maybe to slow, allowing the rest of the house to overheat?

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Unknown

I'm telling you buy these two books;
"Lindharts field guide to steam heating" and "Balancing steam using a vents capacity chart." These two publications will make you understand how to properly balance the steam system. I've used them and they work out great. Of course I've had questions along the way. The guys here have been awesome for helping me "get it." Check 'em out & good luck.

Long Beach Ed

Balancing and Firing

As the others said, balancing is very important. Also, make sure there are vents on the ends of the steam mains. That will insure that all the radiators begin to heat at the same time.

After all that, if the radiators still vent slowly, consider drilling and tapping the big ones for second vent.

I'm not sure how much you know about this stuff, so make certain the boiler is piped to the manufacturer's spec's and that you're using good sized vents on the cold radiators. If the others are heating quickly, you may want to "hold back" the steam a bit on those with slower vents.

Sounds like the boiler is sized properly. If this is a conversion from oil, it will be slower to make steam.

Long Beach Ed

JM_2

remove the vents

If you can spend the time, try removing the vents on the slow to heat rads and see how long it takes for stream to get to them.

Jim Pompetti

How about some pics of the near boiler piping.

mark smith

probably worked this way ... BeFore .....

Mike Cascio

Sounds like the valves are clogged, broken, or undersized on those problem radiators.

How many sq ft edr are those radiators and what is the diameter of the pipe coming in the radiator and valve?

Michael J. Cascio

Angel_2

T.Ferns,

You state that you calculated the EDR heat load for this house. Does that mean a heat loss calculation or did you size up the existing radaiation. Keep in mind that your boiler must be large enough to fill all existing radiators and piping with steam. Many older homes have radiators much larger than necessary.

If you haven't already done so measure the existing radiation and see if your boiler is large enough.

What about pipe insulation in the basement or unheated areas of the house. If that is missing it will certainly affect a boiler that is sized very closely.

If you try to balance the radiators be sure to use variable vent valves so you don't have to replace them to make changes.

Good Luck

Angel G.

T.Ferns

Thanks to all regarding your responses.

1) Yes we performed an EDR load Calc as opposed to a heat loss Calc. Three Times in this case. EDR = 281, Boiler Rating 271. We do 30 to 40 One pipe steam replacements a year. First one in five years that has stumped me.

2) This is a gas to gas replacement.

3) If I can figure out how to get NBP photos on here I will. However we have re-checked simple things like "A" dimension and equalizer sizing. Checks out to the Burnham specs. Besides we don't seem to be having "boiler", condensate, or hammer problem. Just poorly heating radiators. We have removed the main vents we installed just to see if that was having some adverse effect. No difference.

4) The two difficult to heat radiators are 44 sq ft. and 60 sq. ft. respectively. Other radiators in the house are less than 40 and average in the 20 sq. ft. area.

5) We have removed the vents completely from these radiators to see if we have a clogged or busted vent problem and we find only a marginal improvement.

6) This is a well insulated piping system. We often run into systems where a well meaning homeowner has had thier asbestos removed., Not here. In addition these radiators are relatively close to the boiler.

7) Yes this may have been exactly what was happening before we changed the boiler! However, it is our customers perception and comfort that are of paramount concern to me.

8) We are largely self taught here having attended some Dan seminars and each having well used, read, and loved set of Dan Steam Books. I have only recently learned of Mr.Lindert and his books. We will certainly be purchasing them. In the meantime this may in fact be a balancing problem. Drilling, tapping, and installing additional vents in the larger radiators has been suggested to us and is probably our next step. It is the fact that these radiators perform poorly with the vents out that has ne hesitating.

TJ

David_26

Have not seen description of where problem radiators are

Disclaimer- I'm more used to tuning turbine engines. Bought my first house with steam last May and I've been having fun all winter (or I had fun the first few weeks).

It seems you are getting steam where you don't need it. Quoting Dan, try some Hoffman #40 vents on the six radiators that are getting the heat. If you want to experiment before you buy them (probably not on billable time, but I'm not thinking that way) plug a couple of the vents on the good radiators off and see if the problem radiators get warm faster.

Long Beach Ed

Just like David says..

Try limiting the venting of the hot radiators... There's only so much steam to go around.

Also, just take apart the valves of the cold ones on the longshot that they are sticking closed.

Sure that the water's clean with no oil on it and the header arrangement is correct? Dirty water will do this.

Long Beach Ed

Christian Egli_2

My fashion sense about one pipe fittings

I believe the homeowner, she loves her steam radiators and her account of how they keep her hot is most likely accurate. If she didn't know anything, she would have called one of those forced air people to do a job on her.

Here is what I think happened.

I am assuming the big radiators are the first exits on the main, the smaller ones come further down. As it stands, I am also assuming there is nothing wrong with the individual venting scheme on each radiator, you've also tested this, and after 90 minutes of run most of the squatting air should be evicted. The venting phase is over. Thus, there may be a venting problem but no venting solution.

Think distribution

Where does steam always go? Where it is most welcome. Where is that? (1) Whichever way offers the least flow restrictions and (2) wherever you remove unbreathable air. Your open radiator vents do a good job of that, and your two main vents do an even better job.

And that's what has changed.

With good main vents, the steam gets to every radiator within the same amount of time and with nearly the same amount of effort. The rest of the trip is through the kinked valves and through the radiators. This is where an important difference appears between one pipe radiators.

Everything about valves on one pipe is big. 1 1/2, 1 1/4, (1), nothing much smaller even on small radiators. This means small radiators are fitted with gates that are often plenty large for all the traffic they'll ever see. On the other hand, even though valve size is bumped up accordingly, the large radiators are rarely given the opportunity to have anything more than a gate that is properly matched to steam and condensate traffic.

The large radiators are dressed with the tight fitting T-shirts that Simon Cowel of American Idol wears, while the small rads are walking around in the baggy pants that fall to the knees. All clothes that fit, the effect however, is very different.

This is the fashion show going down your runway. The inflated radiators may be the ones offering the most condensing head space but the struggle to get up there through the tight fitting valve is not worth the wait for the steam that chooses the easy targets that the smaller and loosely dressed radiators offer.

Before the time you had any main vent, the steam arrival time to the small and distant radiators was naturally slowed, and thus, the two big radiators would have gotten an initial fill of steam and would have temporarily satisfied for heat. Once the system would have been purged of air, the steam input to these two radiators would have dropped a little and fallen to the current level. Does the owner remember this pattern?

Try plugging the main vent to see if this restores that old pattern again.

To convince yourself it is not a boiler output problem, close one of the large radiator to match your load calculations more exactly and see what happens. However, a grossly oversized boiler would handle this distribution problem in exchange for a less than ideal situation.

Good main vents are key to quick and efficient operation. I would not remove them permanently.

Definitely check out the valves and the riser sizing and pitch on the large radiators. If no easy improvement can be made here, then I would install thermostatic valves on the some of the small radiators.

A new post a few days ago showed thermostatic valves for one pipe that go on the supply side, not on the vent. I think this would be of great interest to you because a thermostatic valve on the supply side allows for constant modulation unlike the thermostatic valve on the vent that modulates with boiler cycling. Since it is already established you do not have much cycling at all these supply side valves should work wonders for you.

The valves have a condensate by-pass with a check all built in. Thank Kniggit.

http://www.ammarkcorp.com/valves1.htm#90.125

That's for one big theory, here's one more:

You all know how hot air ducting is fitted with multiple dampers to direct hot air to the desired air hole. Well, steam flows the same way air does, why wouldn't we have dampers within the steam main? (condensate dribble not withstanding)

I have long thought a method to obtain this could be built on inserting adequately sized pins into the main. Easy and straightforward with a little handle on fluid flow and drag.

Call it main acupuncture. The big idea: with equalized flow it would then be possible to run systems on undersized boilers.

Anyone interested in investigating this further with me? Thanks for getting in touch, the super bowl XL (see it's all about size) isn't starting for a while yet.

charlie_14

dead & dying radiantors

what if this still doesn't do it?
what else sould i try?

Brad White_28

Christian,

you are one damn fine writer. I enjoy reading your postings and the way you break things down logically. Just wanted to say that.

Brad

Ron Schroeder

Run legnth

I have seen many systems where the closet radiators are on the longest runs, if this is the case would it pay to vent the run as close to the radiator as possible?, Im no real wethead a driphead at best..