Oversized or not oversized?

John Doll

We recently had an addition put on our house and it is clear (thanks to one of Dan's books and some feedback from this site) that the plumbing sub is not a steam expert. I do not think he is a complete knucklehead either, but he definelty could use a refresher course.

Our contractor has been working to help us resolve the issues which include a poorly designed/installed hot water loop off the boiler and cast iron baseboard installed with copper pipe and no separate wet return on a one pipe system.

The problem is that they are chaulking the remaining issues up to an "oversized boiler". I want to try and see if this is true and I have call into the installer. (We used PSE&G and it is hard to get a call back although easy to get a service guy). Anyway, my boiler does not seem to short cycle. I want to measure the radiators to determine a reasonable estimate of the system needs. Dan's book has a table that I can use for most of my radiators. However, I have slant fin 1 1/4" cast iron baseboard and some recessed convection type units. Does anyone have a rough measure of the heat load per foot for these?

Thanks.

Brad White_9

I do not have the Slant-Fin CI

radiation output but Noel might... For Burnham CI baseboard it is (IIRC) 3.33 EDR per linear foot. For the recessed type (5" deep by 20" high) it works out neatly to one EDR per inch of length. (2.25 EDR per 2-1/4" long section), so how cool is that?

GW

steam

I'm trying to understand the sizing issue versus the piping concerns. Are these two separate issues?

>>>>>Our contractor has been working to help us resolve the issues which include a poorly designed/installed hot water loop off the boiler and cast iron baseboard installed with copper pipe and no separate wet return on a one pipe system.

Steam baseboard with one pipe? Whose idea was that? I'm confused because if you had a HW zone installed why not just run a baseboard or HW rad off of that? No wet return is fine as long as the unit is pitching with the slope of a ski jump.

>>>The problem is that they are chaulking the remaining issues up to an "oversized boiler". I want to try and see if this is true and I have call into the installer. (We used PSE&G and it is hard to get a call back although easy to get a service guy). Anyway, my boiler does not seem to short cycle. I want to measure the radiators to determine a reasonable estimate of the system needs. Dan's book has a table that I can use for most of my radiators. However, I have slant fin 1 1/4" cast iron baseboard and some recessed convection type units. Does anyone have a rough measure of the heat load per foot for these?

Again I don't follow; did this plumber install the boiler or was it already there? If it doesn't short cycle, are you thinking it should?

If you can't track down the heat values for the odd-duck emitters, here's a lame but useful trick: can you compare that room to a similar sized room the best you can and try to back into a heating output? Usually when it gets down to the last small funky bathroom radiator/convector, it 10 times out of 10 doesn't kick the boiler to the next size.


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John Doll

Pretty cool -

Thanks

John Doll

Sorry

I am so piped up full of steam information that I am spitting out all over the place (much like the one pipe steam baseboard).

There are piping and system concerns. I got them to agree to remove the copper pipe and put a bypass line on the hot water loop. The problem is that the did not follow the diagram I provided and put the pump between the boiler and the loop. I have some other threads on this and from everything I read I know what the piping issues are. The plumbing subcontractor is telling the general contractor that my remaining issues are because the boiler is oversized. I don't believe this to be true and I want to show him calcualtions to prove it. I think he might pay for a pro to do the work if I can refute the "oversized" arguement. They insalled a new steam base board because thr project involve an addition and renovation. They thought it would be easier to install a steam unit in the renovated area because of its location. I learned a lesson about being more specific in the contract. Remaining issues are:

- no wet return on the one pipe steam baseboard
- flashing to steam and rigged hot water loop
- water hammer (I have uninsulated pipes as well)
- uneven heat (I have been changing out valves on the radiators and return to try and correct with some success)

Thanks.

GW

OK

you must be piped up because I still don't follow, and i only sipped down one brewsky (I'm not normally home this early). So, please answer: The copper pipe, was this steam or HW when he thought he was done? I'm guessing steam and they're gonna pipe it w/ steel, am i right? If the system has a HW loop off of it, what does it serve? What on earth does the cycling issues have to do with this? Any steam boiler will have cycling going on. Is the boiler new or old? So, the one-pipe baseboard is different from the hw loop issues? I understand the one pipe baseboard issue, but what is up with the new HW zone? banging and noisy? I must be too tired to follow.

when you say >>>no wet return on the one pipe steam baseboard - flashing to steam and rigged hot water loop - water hammer (I have uninsulated pipes as well) - uneven heat (I have been changing out valves on the radiators and return to try and correct with some success) To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mitch_6

Boiler over size most likely

will not cause banging just short cycling. Since it is oil you may also be able to down fire a little.

I have not used cast iron base board on one pipe steam for a while but I believe you are limited to about five feet and it must be properly pitched.

On the loop hammering you also may have a control problem limiting temperature.

With information given it is tough to diagnose without a sight visit.

Mitch S.



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John Doll

OK

Hopefully we have both sobered up. I'll try to separate the boiler sizing, steam issues and water issues:

Boiler sizing:

The boiler is new. It was put in service last winter. The cycling question came up because the plumbing sub is blaming all of the remaining problems on the boiler being oversized. I am trying to see how much net output my system needs vs the boiler capacity to help focus the GC on the real issues. I don't think the boiler is ovesized because it does not seem to short cycle. I am running a .5 psi with a 1 differential. Is my assumption about the cycling valid?

Steam:

- yes they used copper on an 8" section of cast iron base board and they agreed to replace the copper pipe. Unfortunately, the pipe makes a surging/water hammer sound and spits water. It also does not seem to heat up very well even though it is the closest radiator to the boiler. I also have other issues that are new to the renovation. Uneven heat and more water hammer

Hot Water Loop:

In addition to installing the new steam base board they put a hot water loop onto the boiler to heat a second floor addition. The loop is makes alot of noise. I got them to install a bypass line which helped. But, they installed the pump between the bypass line and the boiler and undersized the piping of the bypass line. I compensated for this by fully opening the valve on the bypass and throttling back the feedback into the boiler to about half way. This reduced the noise in most circumstances. I am not sure if it is a good fix.

John Doll

What do you mean by a control problem? Do you mean the aquastat is not cutting off the boiler befroe it produces steam? How can I diagnose/correct?

Mitch_6

Are you properly controlling the boiler

if not wired properly you could be running the pressure to high even if the pressure switch is set .5 to 1.5

Items as simple as a clogged pig tail can cause havoc on a system.

Best to let someone that knows steam and controls take a look.

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