Modcon Vs CI Combo - HVAC - Contractor Talk

Modcon Vs CI Combo

 
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Old 01-04-2019, 10:25 PM   #1
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Modcon Vs CI Combo


So where does one start?
Well since I'm a ho with a 40 yo cast Weil standing pilot owner of an old gravity fed conversion who has done about 3 years of observations and tweaking of said house and systems..

This has become a hobby of mine.
I've done several heat loss calc and come up with the same things.

Heat loss calc vs delta t makes no difference to me as long as the boiler isn't condensing and house is warm.
Problem for me is the 3 spd grunfos. I keep adjusting the circulator speed to minimize the short cycling.

Mod con makes so much sense.
Try controlling 2 ci boilers.

Redundancy I like.
Simplicitly I like.

No simplicity in control of 2 ci boilers.
Technology must be a big part.
Yet. 2 ci boilers with only one working would still give me more heat than one mod con not happening at all.

It's a tricky complicated situation isn't it?


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Old 01-05-2019, 07:07 PM   #2
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Re: Modcon Vs CI Combo


A nice mod con will give far more even heat in the house than 2 cast iron boilers will.

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Old 01-06-2019, 02:07 PM   #3
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Re: Modcon Vs CI Combo


Been there.

I believe that to be true. I have some control of even heating through balancing and circulator speed control.
I seem to be focused on that for several reasons.

First one being contractor.

If I could find one like most of you here I would more than likely have no fear in having a new system installed as you would advise.
Why?
You are obviously passionate about what you do or wouldn't be here. I'm sure it would be done right and I would have the backup service I would need.
I figure anyone that could do a mod con right would also be the right person to install 2 ci units correctly as well and that person would likely advise the mod con anyhow!

The biggest reason(s) I am thinking this way. Redundancy. Some heat is better than no heat. When we moved in here 3 years ago I was still living 1000 k away and wasn't home much. So I called one of the 2 local heating guys to come in and check the system out. My wife was here alone. It was November and beyond -25 c when they shut the boiler down. It took them over 2 weeks to get the chimney liner replaced. Luckily we had several heaters and a few electric fireplaces.

Redundancy. We were lucky. I explained to my wife over the phone how to strategically place heaters and fans to keep the plumbing and herself from freezing.

Two days later I come home. My shampoo was still partially frozen on the second floor. Wife was still cold.
Then I noticed there was almost no heat on the second floor.
We were now up in the +55 range and holding strong. I called them. They said it would be about a week before they could come out. I let that appt stand and went to work.
First thing. Bleed the rads. Second. Why was the boiler short cycling every 5 minutes or less? 2 aqua stats. One circulator. Circulator stat was set to shut down at 130 ish. High limit is the other one. It was set at 140 ish. So I started first by turning up the high limit until the boiler ran fairly steady. Then took my heat gun and started watching delta t and adjusted. Did not want return temp below 135, which it almost always was before ( I still can't believe this old weil isn't completely rotted out!) I quickly learned how to get good heat and some form of boiler ( cold start boiler, circulator low limit and boiler high limit shutoff no bypass at all) and my nice new chimney liner protected and get good heat but it's not a lot of fun running downstairs every 15 minutes to change speeds on the pump!

This is just the tip of the iceberg and this is a highly recommend and reputable company but it seemed that for the most part I was on my own. The other contractor in town, also reputable and highly recommended called me almost 2 months later. The company that started the work and said it would be a week called 2-3 weeks later. They are just that busy.

I'm trying to give you a picture of why I'm thinking the way I am. Why I'm thinking 2 boilers.

So the contractor who did the chimney liner calls back. I told them we are now heating fine but would like a new boiler quote. They owner came to do that. 20 minutes later he was gone. Yes I trust experience but after an over 14k quote for a TT solo 110 I had a couple of questions. I told him that from what I see online that this is one of the most controversial boilers and I simply wanted to.know if they had installed many of these.
Never heard from them again. Would not answer my emails.

I don't believe everything I read online, but almost all bad reviews about mod cons are due to installer error, lack of knowledge and understanding, lack of time or poor customer service on the part of boiler companies.

CI on the other hand are not as sensitive but I am comparing standing pilot and new CI technology, which is still a lot more simple than a mod con.

I'm not afraid of technology almost anywhere but here. It seems that I would rather have 2 small.simple boilers with xternal controls and a proper primary secondary and thermostatic 3 way mixing valves with bypass for boiler protection etc.

Sorry for the book. Lol
Just have the need to give you an idea of my situation.

Now the 2 facilities I worked at had several boilers, all different types of HVAC systems and it seemed the only ones that kept working with almost zero issues were the old older and oldest non modulating ones.2 and 3 year old Engineered air MUA were failing and it took a lot of troubleshooting to get them working and it seemed like someone was always working on one of them while the camus two stage and super hot single stagers kept on heating.

Finding the right contractor can be extremely difficult. There aren't a lot of guys like you around.

This is why I'm geared towards 2 simple CGA'S two ecm variable circulators and maybe a tekmar two stage control with DHW control. Along those lines.

One working boiler is better than none at all and troubleshooting a bad circulator or simply temporary bypassing and allowing gravity to once again do all the heating in this 82 gallon converted gravity system will still work if at least one boiler is firing.

Situation. I'm a worry wort. Lol
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Old 01-06-2019, 07:13 PM   #4
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Re: Modcon Vs CI Combo


LOL.


Not really anything wrong with KISS technology.


Plus redundancy has its advantages.


Your current boiler will work best with a 20F temp difference. Whether or not it short cycles the burner a bit doesn't matter.



New CGAs will be the same, as far as just get the temp delta they want. When its warmer out, the lead boiler will have a shortened run time.
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Old 01-06-2019, 10:46 PM   #5
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Re: Modcon Vs CI Combo


Well I can manage 25 delta t with this grunfos 15-58 on speed 3. I need 3 and a half to hit that 20. Lol

No bypass either. Just direct return but there are 6 feeds and 6 return lines all meeting together at reducers to and from a common line to the sediment bowls.

So one supply one separate return into what looks like homemade six inch diameter sediment bowls.with no drains and pipes welded to them of course. These are threaded to large reducers. Hard to explain.

There are actually two lengths of 1.5" pipes 23' long that are threaded right into elbows up to the reducers near the boiler with no unions or couplers. That's 23' of straight pipe with no breaks on the supply and return and there are more.like this so the only way to change the existing valves is to cut all pipes one by one then unthread everything. Yup its gonna be a fun summer I can see. Lol
It all has to come out because there is no shut offs and only 2 unions on all 12 lines. Well there are shut offs about 115 years old and all were threaded from the boiler up or rads down. It's a huge pain to change a valve at any rad. The return side at each rad has a normal elbow not an ell.

When I do change one I have to drain the system and cut a pipe off in the basement, then unthread that piece of pipe, then add coupler, union, ball valve, nipples and get length threaded, tee and drain on supply and return just for maintenance. That's the biggest issue is the lack of shut offs and changing all of that is a big job. To get around it so I can isolate a zone I have to cut pipes after the near boiler piping so I can drain that zone and keep the rest of the house warm. I've done a couple of them so far and trust me, those 1.5" pipes that have likely been there since the house was built in 1904 don't wanna come off easy. 24" pipe wrench with a telpost snipe and torch. Lol At least the new stuff has threaded right in but somethings gonna break one of these times.

I'm thinking mixing on the primary loop through a ESBE 140 degree thermic three way on the bypass to the return...
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Old 01-07-2019, 12:35 AM   #6
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Re: Modcon Vs CI Combo


Insulate the piping in the basement, send the heat to the living spaces....

a 2000 Btus here and 1000 Btus there = real improvement for the kids and Momma.

Next year, think about getting the brick treated with a water repellent surface treatment, It will lower the perm ability of the 100 year old masonry...

Time to consider tuck pointing the whole house?

Stucco over 2-3" of foil face rock wool? ~20-40K$ around here, another wythe of brick with a cavity & foam would only be few thousand $ more.
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Old 01-07-2019, 05:53 AM   #7
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Re: Modcon Vs CI Combo


Fourth Gen.

Now there's some stuff I didn't know.
I've done some sill plate insulting and had a few odd main floor side walls apart and insulated with the dap spray foam kits, fiberglass and/or blue board and vapor barrier. The dining room and pantry (2015' ttl) needed it pretty bad. The pantry had a poorly insulated roof above and the dining room has a roof above a window lined alcove that only had wood shavings. These two things have made a big difference. I'll have a good look at getting that stuff done.

Wasn't really sure if I should insulate the pipes downstairs but now I know.

I have over 350' of 1.5" pipe down there and just figured it was what was helping warm the main floor hardwood. Basement w/o insulation never gets below +52 f and that's even at -40 out but I never thought about the permeability of the brick itself. Foundation is 18" stone about 2' above grade.
Basement isn't and will likely never be finished but that doesn't mean it can't be fully insulated. I agree that should be priority in some ways, but I'm sure this old weil is not gonna last much longer and since the pocketbook isn't bottomless the boiler needs doing first! With heat loss based on future improvements of course. We have more than enough electric heaters we can use on those - 40 days if the boiler (s) are temporarily too small.
So far my calcs tell me at present two cga 25's are almost big enough but I'm going to redo that heat loss. Simple. I have all window wall and room sizes as per slant fin and the few things I have already done with sealing and insulating have made a big difference.

Thanks guys. Appreciate the guidance. More than you could know.
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Old 01-07-2019, 05:55 AM   #8
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Re: Modcon Vs CI Combo


BTW I'm not stuck on weil cga. It's just common here and I have faith in weil.
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Old 01-07-2019, 06:17 AM   #9
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Re: Modcon Vs CI Combo


Had to look up tuck pointing. Lol

I've done a little bit. Mostly on the stone foundation and some bad spots. I found an actual 86" chunk of stone completely missing under a deck in the foundation. Could see right outside!
Work in progress and no more mice.
Cats look kinda bored now.

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