Radiant heat and DHW neophyte question

Perry · February 2006

Have just purchased a home built in 1926. Living in Winnipeg Canada, a place where good heat is no joke! Home is 2400 sq ft with a variety of radiators and baseboards thrown together over the years. The house is not cold, but cost $400 per month on a plan for NG. The monster in the basement (at least it seems like one to someone accustomed to forced air) is a 225000 BTU boiler installed approx 40 years ago. There are some larger pipes down there in this two pipe system, (likely 3" iron), so my assumtion is that this was once a gravity steam (if such a thing exists) or water system.

Presently the boiler feeds two zones. One is the entire two floors upstairs, and one is the basement, and a sunroom (which has quite poor windows and insulation making room temps only up to 60 deg and often cooler. Couldn't shut down that sunroom zone for fear of pipes freezing).

Have purchased a Trinity high efficiency 150K btu condensing boiler to replace the old one. It will be direct vented and hopefully with an outside temp reset. For DHW, am looking at an indirect 40 gal tank, (not sure which yet but know Amtrol is available here, and basically will decide based on whoever seems to have the best/most inuitive controller.) I have two circulation pumps that are new, one for main heat and one for DHW, And I assume I'll use one of the old pumps (Grundfos pumps that aren't really that old) for the sunroom basement zone.

Since there are likely many things I need to know about and don't even know to ask about them, will start with requesting recommendations for an indirect DHW tank and controller, and any other advice that seems to you I might need prior to embarking on this project. I think getting the right person to do the job is going to be my best bet in the end, but have been told that if I can do plumbing and wiring this would not be too big a job.

Your thoughts and advice are appreciated,

Perry

Brad White_38 · February 2006

Perry

What is the calculated heat loss of the house? (Excuse me, Hyoose

) On what basis was the NYT Trinity sized?

At first blush it would seem that the original 225 MBH system was a lot for a house that size (75 BTUH/SF check figure at 80% net output). I would expect to see a number in the range of the mid 50's PSF for your area (-26F design temperature), again as a check figure only. Your Trinity sizing at 150 MBH input is right in there. But point is, was this calculated and reflective of insulation and envelope improvements?

Do you know the system to be hot water? Yes, there was gravity hot water (we own you Canadians for that invention, thank you). Gravity steam? I suppose you could call it that but technically no such animal. Just make sure you have hot water to start with. The pipe sizes lead me to think gravity HW. Most steam piping for a house that size would be in the 2 inch, maybe 2.5 inch size from what I have seen.

On to DHW: Several good manufacturers are out there. I own a SuperStor made by Heat Transfer Products down here in tropical Massachusetts. Amtrol, Bock, Viessmann others I am sure you can find. Nothing too fancy in terms of controls, it heats water. You may find features regarding time of day and pre-use boosting but there is not a lot too it really.

And I would not over-size the boiler for the sake of the DHW load in an average house.

Hope this helps!

Brad

EDIT: Posted PDF of weather data for Winnipeg just for fun

Perry · February 2006

Neophyte questions

Thanks Brad,

The boiler was sized, in a rather unscientific manner. I had four contractors do an estimate on boiler and DHW replacement. Each measured all lengths, heights and counted the number of tubes in each rad/baseboard. One contractor said stick to 225 K, one said 200K and one said 150. While the one who stated the least wasn't the lowest bid, he did seem to be the most knowledgable and had in fact worked on the old system in the past. Essentially no upgrades have been done as far as I can tell, to the envelope other than some attic insulation (which may include alot of UFFI dust covered by some fiberglass).

The system is hot water for certain as there are no relief valves at mid height on the rads, and water comes out of the small spiggots that are located at the tops of the rads.

The thing that has me buying my own boiler via the internet, and even considering this kind of project on my own, is the 13- 15000 dollar price tag after taxes that the heating companies came up with. Can't help but feel like that's an awful lot.

My next questions would regard draining the system. I hope it's as simple as turning off the intake water and opening the drain on the boiler. Is comperssed air need to help things along, or will gravity just do it's thing? I would like to flush the system as I hear thats a good thing to do prior to installing a new boiler. Again I'm hoping that flushing the system is not any more complicated that refilling the system and draining again, though with my lack of expertise, won't be surprised if things are more complex that that.

Thanks again,

Perry

Thanks for your reply

Brad White_38 · February 2006

Boiler Sizing

Perry, Hi-

From the sound of your contractor interface, the notion of the highest bidder being more knowledgable is a key aspect. He probably did take into account the full measure of the house. Measuring and following the radiation and calling it a heat loss in a hot water system is extreme folly; accuracy be sheer luck. Using actual radiation is applicable to sizing a steam boiler, however.

First thing I would suggest is insulating the envelope, walls, thick in the attic just because you can. Caulking and so-on.

It may be moot from a boiler purchase standpoint at this time (seems you already made the purchase). If over-sized, modulation is your friend. Still for future reference, size the boiler to the net heat loss plus a squeek for piping pick-up and a safety factor, not more than 10% I would say.

We do not as a practice discuss price on this site, but what you cite especially in Canadian dollars (70% of USD) does not seem out of line especially in that you are a "captive audience" in a cold place, for a full system replacement.

Draining the system is a matter of opening low-point drain valves and opening radiator vents to allow vacuum breaking hence gravity to work. I would not use compressed air except to pressure test the completed piping system. (You are doing this over the summer, right?).

Flushing and treating the piping, especially if that old is a concern. You are introducing oxygen where none has been seen since Dieffenbacher was PM

Accumulated sludge or mud may appear. I suggest you check out Rhomar Water Treatment. Spring for a good Axiom Industries feeder to help with the application. Clean and flush the piping with Rhomar Hydrosolv and finish with the final treatment they recommend. The life of your new boiler will be enhanced.

Best,
Brad

Solarstar · February 2006

Brad ...Where did you get the pdf of the winnepeg data I'm interested in wind data for my area Paul

Brad White_9 · February 2006

Shhhh....it's a secret!

Hi, Bailey-

Actually it is public data compiled by our U.S. Air Force, 30+ year average weather data which is critical to logistics all over the world. (Bases, fuel consumption and all that.)

The CD-ROM is available for $75 (a couple of years ago) via the NOAA web site. I do not have the link handy.

But if you want a particular location I will see what they have. It is public information courtesy of US Taxpayers (you are welcome) so I can distribute without a problem.

Mostly the data is from airports for non-military areas and of course air force bases.

Let me know. You can contact me off-line if you like, just make sure you have a clear message header so my spam filter does not bounce you.

Brad

ChasMan · February 2006

Just as an FYI, It is 87% of a US Dollar. :-) That seems high to me. Id say there are some equipment differences and or scope of work differences. No P&H contractors in Winnipeg are getting 150.00 US to solder pipe together like they are in NYC.

Brad White_9 · February 2006

Good News

You can tell I do not play the money market game too much...

I have this $20 CDN bill sitting around which I acquired about three years ago when the exchange rate was about 70%.

I'm rich!!

But to installed cost, Canadian taxes are a tad on the socialist/confiscatory side last I heard. Health care being one of the bennies...if you survive the wait, you weren't going to die anyway

Perry · February 2006

Bioler sizing and my apologies

Thanks for your advice again Brad. My last home was a 1200 sq ft two story that I had done everything to in terms of insulation icluding walls attic and new windows. It cost $180 to heat in the coldest months, and about $12 during the summer, (likely for hot water). Insulation is high on my list for this house, but I thought that if I was going to be going through so much fuel before I could insulate, at least I'd do it efficiently.

Will look into the system you recommend for flushing etc. Maybe I might be able to rent one, since I likely will only use it once.

Your knowledge of our prime ministers is impressive! For water that's been in there so long, I'd have suspected it to be quite black, and it's clear as can be so I believe one of our more recent prime ministers was in office when this system was last flushed. Do I need to do it again? Actually I don't see any easy shut off valves anywhere, so I may have no choice but to drain everything down anyway.

In fact, I was thinkng of the project ASAP as this winter has not been a very cold one. The thought of all that gas essentially up the chimney kills me. Will obviously have to work out alternate heat and drain the sunroom.

Lastly my apologies for breaching a code I should have read about regarding pricing for work. I was going to correct you about the .7 dollar, since we were there so recently, but am glad someone else was able to first. And congrats on the windfall! We have new $20 bills up here now, so who knows, you may have a collectors item on your hands as well!

ATB

Perry

Brad White_9 · February 2006

No worries, Perry

The pricing discussion thing is sort of an unwritten rule and respects each contractor's integrity in their marketplace. What is charged in NYC where costs tend to be high anyway might seem outrageous in Peoria. (Poor Peoria... national benchmark of unfair comparisons...). What is charged in Beatrice, Nebraska would seem a steal in San Francisco. Every area has it's burden, overhead, labor costs so at best we keep it general if broached at all. I am guilty of the transgression myself.

Your last home seemed to benefit greatly from your work. I hope the current owners appreciate what you have done. I would love to have heating bills like that in my house (6000 Degree Days) even in the 1980's.

Still it would be good to have a calculated heat loss; from there you can match heat loss to your radiation and from there set the boiler heating curve to the optimum. It is universal information to have and you can also extract from that the payback on your insulation efforts.

As for water treatment your idea of "doing it once" has merit. It seems you are secure in knowing that your system is tight. That the water is more Mulroney to Martin Era may not be true. If the system is corroding it would look like that day three. It is a Hobson's choice; you clean the system you may loosen up stuff that might otherwise stay put. But you run the risk of installing your new boiler and have the stuff you cannot see attach to your Trinity. See what Trinity suggests for water pH and composition. Rhomar is a good product line; their 922 is ideal for mixed metals and PEX. Not sure what you may have but I think they have it covered.

Whenever I fill my system I run it through a 5 micron filter (plastic GE type) so at least it is free of particulates and chlorine as far as I can tell.

You may also want to take the opportunity to add ball and drain valves at branches and -especially- TRV's at your radiators while you have the system down.

Glad your $$ is up! Still I will have to visit again soon.

Stay warm and keep me posted, Perry-

Best,
Brad

Radiant heat and DHW neophyte question

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