Preparing ahead of time for a boiler replacement...

Thanks guys, some followup questions...

Will have to look into boilers more... looking at circulators a bit, and thinking about my system... Using the rule of thumb of 4 ft/head/100 ft piping +50% for fittings, etc, I would have about 8-9ft of head to get to furthest radiator (140ft x 6/100ft).



I know the rule of thumb starting point for most systems is 20 Delta T, but also that some systems seem to run better on higher. An all CI radiator system you would say should be around 40? Can you give me a quick/easy explanation why (not arguing, just trying to learn)? In sizing, should I size things to handle more like 20 to be safe, then I can dial it in anywhere in that range if necessary? This seems to make a difference in the options for circulators.



Haven't done heat loss calcs yet, but I'm thinking that with added insulation, the fact that the system seemed to be happy to overheat the space (due to high tstat setting) before that, etc, that my actual need will be more like 80k than the existing 100k btuh. So for 20DT, that would give about 8GPM, vs 4GPM for 40DT.



The bumble bee curve shows that at max speed I'd get 6GPM at 9 ft head, which puts me right between those 2 flow requirements.



I wrote down a stamping when I was looking at the boiler/etc - one of the flanges is stamped 110-338 on the circulator, so I guess this is an older Taco 110. Looking at specs on the new ones, they have a max head of 7.5, but flow of up to 33GPM. I don't really know what conclusions to draw from that, but the system seems to operate well with it from what I know. Can I assume from this that 7.5 ft of head would be more than sufficient? The bumble bee that you both seem to like would give me almost 8GPM at that head.



Also, is there any merit to the thought that higher pressure pumping helps balance out a system like mine, where there are no zones or anything - enough pressure forces water to get to the higher resistance radiators? Would a smart pump/higher DT w/ lower flow rate possibly create balance problems that didn't exist with my old on/off pump?



As for dirt/air separation, the Caleffi you mention Rich is a hydraulic separator, right? I'm not sure I understand the purpose/benefit of these in general, but particularly on a system w/o multiple pumps. Is this something I need? Any thoughts about the Spirovent separators (sep air and dirt ones) or any other brands, if I don't need the hydraulic separator? The boiler you recommend Rich also claims to have built-in air and dirt separators - are these reliable, or is it recommended to put in external ones as well?



As for TRVs, having managed a number of steam heated apartment buildings, using TRVs in some cases, and not in others, I'm not sure that I'm a big fan for this application. In a private residence, they're great - allows you to balance the system just how you want it. In apartments, I've found that every single TRV was turned to 5 (max on the Danfoss' we used), even if it was uncomfortably hot in the unit. This screwed with the balance of the rest of the system. Most times I found it better to take out the TRVs and put in fixed vents of the appropriate size to get the balance I wanted, and not give the tenants any control over it. I assume that they'd function somewhat similarly on a hot water system, but I'm not sure.



Insulation is a given - I'm in process of getting all the mains insulated before winter. This will include near boiler piping, and then i'll have to redo the insulation on the near boiler piping i guess when the new boiler goes in, but it will all definitely be insulated.



Are indirect water heaters really that big of a cost savings? I've been wondering about that for a while. I can definitely see how they would work well in the heating season, but does running a boiler all summer to provide DHW really pay off?



Existing tank is a bladder type, i'd replace it with a new Extrol regardless. On a system this small, wouldn't a 30 be sufficient? Certainly seems like a 90 would be massively overkill, but maybe a 60 due to the high water content compared to today's systems of similar btu usage, but a lot less water?

Relief valve blowing on heat up

Hey all,



I've been busy with other work on the property, so set aside my replacement planning for a bit. In the meantime, I've taken apart the old boiler and cleaned the burners and as much of the heat exchanging surfaces as I could get to. Burners were caked in rust, but the exchange surfaces were surprisingly clean. Anyway, I've also insulated all the basement piping with 1" fiberglass on everything 1" and larger, and Home Cheapo stuff on the little 3/4" lines. Don't want to overdue the insulating, as there is no real heat source in the basement.



Anyway, fired up the boiler a few days ago for the first time this season, all seemed good. When I went back into basement later, the relief valve had been blowing. It def never blew before heating cycles started, and doesn't seem to continuously blow. I haven't stayed around to watch exactly when it goes yet, but will try to do that today. I just turned the system off temporarily so that it wouldn't keep doing that until I could work on it.



I'm thinking the relief valve is operating ok, as it only blows under certain conditions, unless they can get "off" as they age and blow at lower pressures. Nothing has changed from last year (other than cleaning and insulating), when system was running fine. So is my water feeder pumping in too much pressure? The insulation adding enough extra heat to boiler to blow pressure valve? Valve just faulty? Bladder tank failed?



Boiler is set up all wrong, hoping to avoid messing with it much until I redo the whole system... Got pump on return pumping directly into the boiler with auto feed right next to it, and the bladder tank, auto air vent, and relief valve are mounted on top of boiler. Thats pretty much it, its an old school boiler without much on it.



Other caveat, there are NO valves on this thing. No valves for the pump, none to isolate the boiler or controls, most of the radiators don't even have them. Again, I plan to add valves to isolate the pump, boiler, etc when I redo the system, but for the meantime, is draining the whole system the only way to work on this stuff? I really hate to introduce all that new water to such an old system any more than I absolutely have to. I guess if it comes down to draining the thing for this, I should just put in a main valve on supply and return sides so that I don't have to drain whole system again to replace boiler etc in future.



I don't trust the guage on there, as it is quite old, but will try to see if it gives me any kind of readings on cycles today.



Thanks for any help you can give. I need to get this thing back up and running for the winter, then can start planning my full replacement for over the summer sometime. If anyone has any more input on the books of info/questions I posted in above posts as well, that would be appreciated, but not as urgent. Thanks!

One more question...

So I"m a steam guy more than water (by experience, not necessarily preference). I'm not used to working on these systems full of water where opening the system is such a hassle.



Anyway, I was quite surprised today to find that only minimal water drained when removing some of the boiler components. Can someone explain how that works, when there are no valves to stop the flow? Is it simply the difficulty entrance for air to replace the water that makes 2 stories of full radiators above me not come rushing out the relief valve when its open, or the gauge fitting w/ the gauge removed? Does the pump impeller help resist the flow required?



It was a pleasant surprise, and after I was done and bled all the radiators, even more pleasant to find almost no air their either (and they'd probably not be bled in at least a couple years).

Thanks steamfitter

for the reply. I need to figure out how to go about a heat loss calculation, never done one before, as I've mostly done repair work on steam systems, not new systems. Will start to work on that.



Wow, less than 2' head? Is that just b/c of the very large piping? Using the quick rule (6' head per 100' of longest run), i get about 8-9', but that's probably based on more modern lower volume systems?



This is a rental, 2 units with shared heating system where I pay the gas bill. So I don't want headaches and complications, but efficiency is good, as it keeps my long term operating costs down. Some of the simple boilers claim 84% AFUE, is it really going to save me that much in a smaller system like this to go up to the mod/con route? Enough to pay for the huge price bump?



Also, is there value in running a simple boiler with an ECM circulator, or do you kind of need them both to add much value? Some of the pumps like the BumbleBee aren't all that giant of a price increase... if they improve efficiency, would probably pay for themselves quickly. And if you're right about having 2' or less of head, it would be way more than enough for my system's needs. Or do you think stick with a simple single speed circulator here as well?



Any good resources to help an experienced contractor, but newb to load calcs, perform a load calculation? I just found SlantFin's app for Android phones, gonna give that a try... seems decent, but any better suggestions are welcome.