Greetings,

I'll apologize in advance if I get some terminology mixed up. I've searched and searched on this topic and have not been able to get an answer.

some background:
Over the summer I purchased a 1948 brick colonial with a one room addition that looks like it was added in the 80's. There is a gas boiler/forced hot water system with cast iron radiators in the original structure, and copper/fin baseboard in the addition.

Both 'zones' have their own thermostat and circulation pumps, coming off different sides of the boiler (if that matters?).

As winter hit we noticed that the baseboards in the addition never really got hot-so the thermostat would call and call and call for heat. Meanwhile, the radiators in the rest of the house were getting warm (by way of comparision, when the main 'stat calls for heat, the cast iron radiators get HOT)

I put in a call to our utility company ( i have a service contract with them) and their first tech said that my checkflow value was bad and the little circulator for the addition was pulling the hot water through out the whole house. The company then sent out a plumber, he said the value was fine (they almost never go out, he said) but there was an air block on the baseboard loop and that was backing the hot water up to the rest of the house.

Well it's a few months later, and it seems like not thing changed-the little circulation pump works and works, and the addition doesn't get warm, but the rest of the house does.

Any thoughts?

The boiler is about 26 years old. I'm contemplating spending my tax return on a new boiler with an indirect HW, my fear is that the system is set up incorrectly and this will not solve the problem--at the same time, all the research i can find suggests that circ pumps are better for doing multiple zones than zone valves.

Thanks in advance for any insight.

 

What you are describing sounds as though BOTH guys were right... the fact that the 'other' zone is heating when the one is calling seems as though you have what is sometimes called 'ghost flow', where the circ is creating enough of a pressure difference to induce flow in the other zone... typically cured by a properly installed and operating flow control valve.

Also, if the baseboards aren't getting hot, it could also mean that there IS air blocking the flow... when the second tech was out, did he actually DO anything? or just tell you that's what it was and pack up and leave?

Can you post pictures of the system? free account / Image hosting, free photo sharing & video sharing at Photobucket / upload there / drop link to your album here.

What brand/model boiler do you have?

Is there a gray box, appx 4" x 6" mounted on it?

How about the TEMP/PRESSURE gauge? what readings are you getting on that gauge?

 

Thanks for your fast reply NJ trooper.

I dont' have all the info you requested at hand but i'll provide what i can until i get home tonight.

The 2nd tech did bleed the copper loop, i wasn't right next to him the whole time (i was "working from home" that day) but i know he adjusted the pressure on the line but adding some water, he adjusted the temp on the boiler too i believe, he also oiled the older pump on the main loop for me (i guess it's not a sealed unit) he seemed like a knowledgeable guy. We certainly dont' hear niagra falls when that zone starts to call for heat, like we used to.

I'll take some pics this weekend and post.

There is the gray box on the boiler for each of the circ pumps, there is an electric cable going into is as well as teh wire from the thermostat.

this might sound like a crazy overkill solution to the situation, but i'm really tempted to replace the boiler and my direct fire HW with an indirect system--would the flow valve be replaced in the installation (the sales guy said that installation covered 'all plumbing' or should i be sure to call that out specifically with the sales guy?

sorta off topic-the home inspector that looks at the house before we bought it over the summer rated teh boiler at 120,000 btu, the sales guy wants me to get a 125,000 btu unit, the house has original (ie terrible) windows which i hope to replace in teh next 3 or 4 years, insulation is good but not great, and i've done a fair amount or weather sealing already.

my question is, should i go for a smaller boiler or would the addition of the indirect HW make it sound to stick with the 125 k?

thanks

 

jefke, the gray box ... the main aquastat for the boiler, the one with the circ that feeds the zone valves, what is the temperature set to on that aquastat?

Will view pics when posted...

Beware the salesman.

The FIRST thing to do before installing a new boiler is to do a complete heat loss analysis on the building. Then, when that comes in around 40K BTUH, and the indirect says that for rated specs on recovery time you need 140K BTUH, decide how much 'compromise' you want to make on the recovery time and size the boiler somewhere between the two numbers.

If the salesman looks at you like you have two heads when you mention that you would like a heat loss done on the home, or tells you that it's not necessary, find a different guy.

Attic insulation is often a pretty easy DIY job... and that is the first place to add insulation. R40 minimum.

If you replace the boiler NOW, before you do any upgrades to the building envelope, you are going to end up with a boiler much larger than you need. If your unit is still serviceable, stick with it as long as you need to in order to change out the windows and add insulation and seal up the envelope... THEN replace the heating system.

 

Depending upon how far apart physically the aquastat (primary control) and the circ. relay are, it's possible the t-stat wires are reversed between the two controls.
Nah, that would be too simple...
Tom Beer 4U2

 

i took some pictures today, sorry that most are not in focus

Boiler - a set on Flickr

The gauge on the outside of the boilder says 70 degrees (the boiler's not running today as it's 75 out) and 100 kpa, i believe

the aquastat is set at 180.

thanks

 

A zone control problem is probably not a good reason to replace a boiler, unless you have a stack of cash in the closet that you just WANT to spend.

 

100 kpa? uh-oh, I was sleepin' when we were spoza be lernin' metric system...

What's that in PSI?

going to look at pics now.

 

sorry, NJ- the gauge is on the back of the unit and in the dark, so i didn't look very closely, to me kpa made as much sense as anything would....

it's at 15 psi.

joewalbran: normally i'd agree with you, but as it were, i just got a once in a lifetime tax refund and while i'm not looking to throw away good money, i'm exploring all options for improving the home and its systems. One of the techs i spoke with said it would be over 1k to replace the check flow valve, when it was all said and done. that was about 25% of the boiler they quoted me, so if i have the money, know i'm going to want to replace the boiler soon anyway....it seems to make some sense, though i admit my logic is not 100% sound.

add to the equation that our current direct fire hot water heater is 11 years old, and really not cutting the mustard anymore, i'd rather get ahead of the curve and replace that with an indirect before it gives up the ghost, and then be stuck with the hard decision of not having hot water for a week or replacing with another direct fire for 800-900 bucks.

if that makes anysense

 

Say WHAT?

Sounds like robbery to me... and that they really want to sell you a new boiler. If 1K is 25% of a new boiler, it also sounds like they are going to 'cut and paste' a bargain basement boiler into your old piping.

I only see one flow check... I can't really tell a lot from the pics... but believe you should have one on each zone.

Maybe try more pics? Some from further back in order that we might be able to 'relate' the various closer ones and get an idea of how the piping is actually laid out?

 

Hmmm can't say for sure the pricing on the new unit it is a columbia mcb 125. It's a conventual cast iron. The position of my current unit seems to dictate that a direct vent for a high effciency unit would be impractical. I dunno much about installing chimney liners but it seems to me that the condensing boilers are better suited for lower heat applications vs radiators and hot water heating. All this be considering.

There seems to be only one valve for both loops. Perhaps the fundemental issue. I'll try to take some more pics.