"New" Slantfin Boiler won't heat house -- from alt.hvac

[TomR]

A person named Nahsani recently posted the following on the alt.hvac newsgroup:

"My two-year old Slantf "My old boiler was ancient - 50 year old, big. Then it puffed back and wrecked my house. Anyway, I only replaced the boiler and the pipes leading into it. It used to work fine (the new one). Although my ex-boiler guy insisted that the on and off operation is normal, I really think it's important. I would say the btu rating is less for the new boiler, but I don't know and I don't know what the old one was. I've lived here for 13 years and it is a tiny house - 810 sq.ft. one floor. Mostly new windows and insulation. The whole house is cold and I have no idea about the piping. The weird thing is that it got my house up to 70 yesterday, for the first time in a long while. Today, it won't get going."

I decided to also post it here in case anyone here has and ideas or suggestions.

[trader_4]

Who knows. It doesn't make a lot of sense. If it's only coming on and off for short periods of time, incapable of raising the temp, then that should be demonstrable when the tech is there, regardless of whether the house happens to be 65. Just raise the thermostat to 75. What happens? If the thing is not coming on, not generating proper heat, it should be obvious. Something here doesn't compute. If the OP has really given the contractor many attempts to fix this new install and they can't or won't, then I'd call another HVAC company to solve it, then sue the original company in small claims for what it costs, if necessary.

Any speculation here seems pointless, no indication the poster is DIY, going to try to fix it himself. One of the easiest things, the thermostat has already been replaced.

[bob_villa]

Tell him to join (for free) at this website:

They've helped me a few times with HVAC questions.

[TomR]

Some of it does seem to be hard to figure out, but one thing that I like in the other alt.hvac thread about this is that the OP has been willing to post back more info in response to questions etc., and that is helping to fill in the picture some.

I re-posted it here because I thought that Stormin Normin and maybe others here may have some ideas.

I was definitely wondering what may be causing the short cycling where his heater keeps cuttin gout and then restarting before getting the radiators hot. I don't know if a bad circulator pump could cause that or if something else is being detected by a sensor of some type that keeps telling the heater to stop and then re-start.

[Ed Pawlowski]

Few possible things.

There is a high limit switch that will cut the burner at a pre-set temperature. That would make the boiler cycle more if it is set too low or defective. If the circulator is not moving the water to the rest of the house it will shut down the burner. If the boiler cycles for just a couple of seconds, I'd first feelt he pipes and see if the water is moving. If not, replace the pump. If yes, check the limit switches.

There are other potential problems but not enough information to discuss. Since the boiler is 2 years old, I have to assume it worked OK last year. If so, that removes speculation about the size of the boiler. It is probably smaller in output, but that is because it is more efficient. If the old boiler was 60% and dumping 40% up the stack, an 85% boiler does not have to be as big.

[TomR]

All good points, IMO. In the alt.hvac group the OP did write back that his "new" heating system did work last year and that the recent developments where it kept short cycling and won't heat the house properly were new. So, IMO, that ruled out the possibility that the heating system was undersized for the house (which he says is small -- 810 sq. ft.), or that the piping system was designed incorrectly (it's the same piping system that the old heater used).

[Stormin Mormon]

Dear Nahsani,

Is the thermostat actually calling for heat all this time? Can you see on the display?

Do the radiators get hot at any point during the day, or only a trace of heat?

Is there a circulating pump on the system?

- . Christopher A. Young learn more about Jesus .

. .

[Tekkie®]

TomR posted for all of us...

No thanks, BAD IDEA!

[TimR]

If the boiler is starting up, getting hot, and shutting off before the house gets warm, one likely cause would be something is stopping the hot boiler water from getting to the radiators.

It could be as simple as an air lock. Or, a bad pump somewhere. Or, bad controller for that pump.

If that were the case, I would expect the thermostat to keep calling for heat, and the boiler to be maintaining its setpoint, whatever that is, and coming on and off just enough to keep the boiler water from getting cold.

[Ed Pawlowski]

I think we pretty much narrowed it down to that. What we don't know is what was actually checked. You can feel the pipes around the house to see if they are hot. Most systems will allow some gravity circulation, but not enough to heat the house properly. Depending on the pump, you may see, hear, or feel the motor running Assuming it is ok, the high limit switch would be my next step.

[TimR]

I'm not seeing why you suspect the high limit switch. Wouldn't that require hitting the reset, if tripped? This boiler short cycles during the day without tripping any safeties.

The old boiler was 50 years old. The boiler was replaced but not any of the pipes or radiators, so they are all 50 years old. They might have worked fine the first year then a chunk of something came loose and there's a blockage somewhere.

[Ed Pawlowski]

The high limit switch shuts the heat off when the boiler water is at temperature. If it cuts it prematurely, it won't heat the water enough to heat the house. No reset required, that is how it is supposed to work to make the burner cycle.

The water cools as it gives its heat to the rest of the hose. Once it get down to the low limit, the burner is started again.

Possible, unlikely. Check the flow as I suggested.

[trader_4]

Is there a Nahsani?

Lots of speculation on little info and what info there is doesn't make much sense. N is MIA.

[TomR]

Yes, apparently Nahsani has "left the building".

Sorry for wasting everyone's time on this one. I decided to try posting this here on alt.home.repair to help Nahsani. And, I only did so because he was responsive in the alt.hvac group where he originally posted his question, and he posted about 5 follow-up posts there in response to questions and feedback that he received on that forum. If it were not for his willingness to follow up on the discussion there on alt.hvac, I would not have posted his question here. However, after I posted his inquiry here, and I also followed up further on alt.hvac, Nahsani stopped following up on the alt.hvac forum or here.

But, I do think that all of your thoughts and suggestions were probably right on the money based on what he described as heater symptoms.

[micky]

Did he ever say he woudl read AHR? He reads through FlashNewsgroups.com, I think, and maybe it's hard to read this group.

Oh, look at this:

The Flash NewsGroups WebSite is temporarily DOWN for maintenance. Sorry for any inconvenience, we should be back up in 2-3 hours. Thu Feb 17 17:15:24 PST 2011 This site is down, but no need for alarm

You were right, it wasn't you.. it was us.

But we're different now, and we really want to change.

Give us another chance, and before tomorrow we'll be a whole new site, a better site, promise. Service should be restored before the end of January 10th

We apologize for any inconvenience.

If you use 70.38.38.40 instead of flashnewsgroups.com, stop. That address will not work after today.

---------------------------------------------------------

He posted from Jan. 10 to Jan 15, so it must have come up and then gone down again.

When I entered flashnewsgroups.com, I got "server not found, but when I entered wwww.flashnewsgroups.com, I got what is above. Normlally FF inserts the www. ????

[TomR]

Wow, that's interesting about flashnewsgoups.com -- whatever that is. Maybe that does explain why Nahsani appeared to have "left the building". Maybe flashnewsgroups.com won't let him in the building.

[TimR]

It appears from the OP's statement that the boiler does get up to temperature, and stops quickly. That argues against the high limit switch I think. It's the radiators that never get hot.

[Ed Pawlowski]

Then you check for circulation. Water has to be moved to distribute the heat. I said before that gravity will move some of the water, but not enough to properly heat the house. The circulator may be working a bit, but not turning fast enough to do the job.

[TomR]

Well, it looks like flashnewsgroups is back up. But, it also looks like people have to pay money to use it and to access newsgroups.

[ray.alexander]

I'd recommend just getting a local heating engineer to come and take a look at it really, after all they'll be able to diagnose the fault and fix it p retty fast usually.

The last time I had a problem with my boiler, I was going to use BG but wit h the call out fee's they mentioned I thought "no chance". I was wondering what to do, then I heard a radio advert for some firm called STL Heating - "well, what the heck" I thought, these guys are local - why not ?

So I gave them a call and thankfully the call out fee was a lot less so I'v e been using them ever since for my boiler service.