How to tell if circulator is pumping?

[calantha]

I have an old Weil McLain CGM6Pi Ser. 7 gas-fired boiler, with a Taco 007-F5 circulator pump. It's the beginning of the heating season. I had a technician here 2 days ago because the heat wouldn't come on. The problem was the damper not opening properly. He got that solved, and did an overall clean and check of the boiler. (He warned me that the boiler is nearing end of life, which isn't a surprise.)

Now the boiler fires and heats, but I'm not sure it's circulating. The pump is hot to touch, which Google tells me is normal. The upstairs radiators (actually convectors) are putting out warm air, but not as warm as I'd expect. And normally especially in the upstairs bedroom I'd hear a water swooshing sound when the heat comes up in the morning. I'm not hearing that.

The gauges on the boiler say the water is 180 deg. F, and the pressure is about 20 psi when it's heating. The technician drained some water out of the expansion tank when he was here because he said the pressure was too high at about 35-40 psi. He also turned off the shut-off valve for the automatic water refill and said it was better not to add new water into the system unless there was a need to.

Sorry if this is rambling. Bottom line is I don't want another service call if it's unnecessary, and I don't want to sound like a silly lady fussing about her boiler. Is there a way I can just check if the pump is circulating the hot water?

 

[Cpeters]

If the pump is on the return side, feel the pipe. The cold water up by you baseboard will be pulled down to the boiler and should eventually warm up
if it is being circulated.

 

[Sponsor]

 

[calantha]

If the pump is on the return side, feel the pipe. The cold water up by you baseboard will be pulled down to the boiler and should eventually warm up
if it is being circulated.

Logical! Both pipes are hot, though the one coming directly out of the top of the boiler case is hotter than the one connected to the pump. I guess that means the one to the pump is the return, and it is circulating.

I'll force it on again (fairly warm today, with the outdoor temp heading up to 60), and get the pressure up, and check the radiators again. Two of the second-floor radiators bled (first air and then water.) One of them did nothing -- no air and no water. Does that mean the system needs more water? Or should I wait till a colder day to determine that?

 

[Cpeters]

To bleed the air out you need water to replace it. Open up the feed a little. Also you may want to look up videos on how to
purge air out of your system. do only when boiler has cooled down.

 

[calantha]

To bleed the air out you need water to replace it. Open up the feed a little. Also you may want to look up videos on how to
purge air out of your system. do only when boiler has cooled down.

OK, this is a good day to let it cool down. I'll do that.

I don't want to start a new thread if this info is already here. Is there a document or discussion you can point me to about how to choose a contractor to install a new one? And maybe a "for dummies" guide to help me with what I need to know to decide what to replace my current one with?

One thing I've learned is that I do better with contractors who are "sympatico" with older houses. My house was built in the mid 40's, but is more like pre-war construction, and has a few generations of different updates. I need the problem-solving abilities of people who've worked on more than just new construction. I plan to ask my neighbors who replaced theirs a couple years ago, who have a very similar house.

Thank you for your help!

 

[Dana]

There are no rocket scientists wasting their careers replacing circulation pumps- most people with some basic tools electrical/mechanical skills can usually swap an 007 as a DIY project in well under an hour. But if you're getting some heat it's clearly circulating some, and the flow problem in all likelihood is related to air in the system. A "swooshing" sound is usually from air in the system- if you're no longer hearing it that may be a GOOD thing, unless it's the case that there is so much air in the system that flow to some convectors/radiators is limited or nonexistent due to a vapor-lock.

The pressure on the system at idle should be about 12psi, and hopefully the tech pre-charged the expansion tank correctly. On high volume systems (=fat pipes, radiators) the pressure might break 20psi when the system & boiler is fully hot, but in most fin-tube convector systems with 3/4" or 1/2" plumbing that would be unusual unless the tank is improperly charged or improperly sized.

It's fine to bleed air from the system from air-bleeder valves while the system is fully hot, just be sure to wear gloves if it's at a scalding temperature, and do it when the system is NOT running. Turn the thermostat down or off.

A typical 1940s vintage bleeder valve will look like this (though there are variations on the theme):

With a finned convector you might find it on the connection plumbing under the sheet metal or near the floor. Some may not have them at all, but they usually do. The small round port on the side is where the air, and potentially some hot water will come out when bleeding the system. The screwdriver slotted screw in the middle is a needle-valve. If you turn it 1/2 turn counter-clockwise it will open up, and you may hear air escaping, some hiss with some water splash, or a steady thin stream of water (have something to catch the water, and have some towels handy for mopping up what you don't catch.)

When it's clear stream and not hissing, close the valve again, move on to the next radiator or convector- there may be multiple locations where air is trapped, impeding the performance of the system.

 

[calantha]

Sorry I wasn't clear. I meant my future need to replace the boiler. The guy said he thinks it will make it through this winter, but I should be prepared that it might need to be replaced. I don't want to be sitting here on a cold day knowing nothing about how to make decisions about it. I know you folks deal with this all the time, but I'm embarrassed to admit I never thought about the need to replace the boiler. It was here when I bought the house and it's been a workhorse all these years.

Thank you for the additional info about bleeding and air in the system. The valves are in a nice, easy-to-reach place on each one, and I have a key. They look like the bottom one, but without the screwdriver slot. Just a square recessed in a circle.

 

[Dana]

If you're going to replace the boiler after this season, be sure to run a fuel-use based heat load calculation on this winter's fuel use. This method uses the existing boiler as the measuring instrument for the actual heat load (distribution losses included). This should NOT be left up to the installers, who most often operate from crude rules of thumb, or perform the load calculations using ACCA Manual-J type methods, but usually with a strong bias toward upsizing the numbers, contravening the direct instruction on how those tools are to be used. If you have some of last winter's gas bills with exact meter reading dates & amounts handy, you don't even have to wait- run the load calculations now, and compare them with this year's performance. This does not take hard math, but it does take a bit of time (remarkably little time, once you've run the numbers once or twice.)

The six plate CGM6 is almost certain to be ridiculously oversized for your actual heating loads, with 175,000BTU/hr in, 140,000 BTU/hr (80% efficiency) . Most homes in NY have heat loads under 50,000 BTU/hr, even old ones. A typical 2000' + full basement tightened up 2x4 framed houses with clear glass storm windows over single pane wood sash with R25 fluff in the attic and fiberglass in the wall cavities would come in around 40,000 BTU/hr @ 0F outdoor temps. If the basement is air sealed and insulated (even if not actively heated ) it would come in closer to 30,000 BTU/hr @ 0F. Most boiler installers would look at the same house and use some crummy rule of thumb such as " lessee, a couple thousand feet times 35 BTU per square foot comes ta 70,000 BTU/hr, but just to be sure let's make it 100K."

I've never seen a normal sized house in NY or New England that has a heat load anywhere near 140,000 BTU/hr, and very few that approach 100,000 BTU/hr (usually large antique houses with little or no insulation, and lots of air leakage.)

Oversizing a boiler that badly costs more up front, is less conducive to comfort, and costs you more every year in reduced efficiency. The nameplate AFUE efficiency is based on duty-cycle testing at a presumed 1.7x oversizing factor, ASHRAE recommends no more than 1.4x oversizing for cast-iron boilers. Modulating condensing boilers can be oversized by a bit more and still do OK, as long as it's minimum-firing rate is low enough that it can be operated at a condensing temperature with your radiators/convectors without a lot of on/off cycling, but that's the second part of figuring this all out ahead of time.

Only when you've figured out the load and the likely replacement equipment is it time to start talking to contractors. And don't be coy about it, TELL THEM what your calculated load is, and the type/size of equipment that you want. Many will try to argue with you on that, and you may have to tell some of those that you're not interested in getting a quote or proposal out of them. Bh

Outdoor design temps vary by location, and NY covers a wide range of climate- where are you located (for purposes of estimating outdoor design temperatures, and digging up reasonable weather stations to use for fuel use load calculations)?

Most air bleeder valves can use either a screwdriver or the square key. If yours don't have the slot for a screwdriver your still good to go as long as you have a key. Even if you didn't have one, they're not very expensive.

 

[Reach4]

Sorry I wasn't clear. I meant my future need to replace the boiler. The guy said he thinks it will make it through this winter, but I should be prepared that it might need to be replaced.

Sometimes when somebody does some work on a system, he gets blamed for the next thing that fails. I suspect he was just letting you know not to blame him if something breaks.

Another more cynical possibility is he was getting you ready for a sales pitch or to cause you to worry enough to call and ask to spend big money.

 

[Dana]

While the boiler may or may not be on the critical list, it was probably installed during the Nixon era possibly even earlier (it didn't even come with an automated flue damper!) and beyond a typical lifecycle. If it's not leaking it could maybe go another 40 years, or it could fail tomorrow, but the cast iron heat exchanger plates have surely seen significant erosion/corrosion on both the fire and water sides, and it's unlikely to be capable of performing anywhere near it's nameplate efficiency. Best case it's running ~75% efficiency (steady-state), and with the likely 3x+ oversizing factor it's as-used AFUE is probably sub-70%. Replacing it with a right sized boiler wouldn't be the worst investment, assuming the plan is to live there for more than a few years.

 

[calantha]

This is great information. I'll pull out the bills from last winter and see if I can step through this.

I'm in southeast Pennsylvania. Looking at the list in Manual J I'd guess at using Willow Grove Naval Air Station. Philly airport is generally a small bit warmer than where I am. I think Willow Grove is closer in temp to my location. I can watch it a bit and compare.

The house is stone, with little to no insulation between the outer stone and the inner plaster walls. Original wood sash windows (leaky) with later triple-track storm/screens added. There's an unheated attic. There's some kind of insulation under the attic floor, but I have no idea what it is. The land slopes so one side of the basement is below ground and the other side is walk-out. Past of the basement level is the garage. The basement is semi-heated -- the utility room and main room get some heat from the boiler and water heater. There's a smaller room, open to the main room, where there's a baseboard, and a powder room with a radiator.

I'm planning to keep the house a bit colder this winter than last year, because of changes in who's living here and what rooms are being used.

To Reach4:
That's possible, and worth considering. But if it does have a problem in the future I don't know how much money it's worth putting into it. I got off easy this time because he got the damper working and only charged me for a routine clean and check service, which it needed anyway. But he quoted $676 if he needed to replace the damper. Is there a typical failure point on the boiler? How would you base the repair/replace decision for this if there were a significant repair needed? Just adding that I'm planning to stay in this house maybe 5-ish more years, not looking to make major improvements that won't pay off for me.

 

[Reach4]

Is there a typical failure point on the boiler? How would you base the repair/replace decision for this if there were a significant repair needed?

I don't know about boilers. Dana certainly does. My comments were more general about somebody servicing a high value item that they did not sell. I think it more likely that your guy was pointing out the fact that things happen, and his service was only for what he did. He sounds like a valuable asset to your home.

 

[Dana]

Keep track of your thermostat settings, since that affects what heating degree-day base temperature make sense for calculating the load from fuel use. If you have some bills from January through March of this year and your approximate thermostat settings I could walk you through the load numbers.

The sorts of failures that require replacement are when it begins to leak water at the seams between the plates. Sometimes those leaks can start out slowly and undetected, but once it starts puddling on the floor it's time to get serious about it.

Retrofit insulating the walls of old stone houses can be a real pain, and often expensive, usually only done when the plaster is shot and the finish walls need to be re-done. But air-sealing will always be cost effective (at least on the first pass of blower-door directed air sealing efforts) and it's likely that more insulation could be added to the attic. If you have any sort of weatherization budget it's worth getting some quotes & proposals for air sealing from an insulation contractor specializing in those services (not all insulation contractors have blower doors and infra-red cameras.)

It's also usually cost effective over the longer term to insulate unfinished basement walls with 2" of closed cell polyurethane spray foam, but it can be an expensive prospect if there are not state & local subsidies for that. Even when not actively heated an uninsulated basement is still a significant fraction of the total heat load.

The 99th percentile temperature bin for Willow Grove is going to be somewhere around +13F give or take, the 99.6th percentile bin around +10F. Using an outside design temperature any lower than +10F for load calculation purposes would not be legit, even though it sometimes drops into negative single digits during the 25 year extremes. With even a 1.2x oversizing factor for the heat load at +10F you would be more than covered at 0F, and a 1.4x oversize factor would have you covered into negative double-digits F.