Mod CON? Or Power vent 85%?

Gordy

A lot of bantering going on here.

Keep in mind that an 85% rated Ci boiler is NOT 85% efficient all season long. There is also "system efficiency" to consider.

When a boiler does not have the ability to modulate to lower loads below design, and short cycles when emitters with out mass, and low load zones are used their efficiency goes south in a hurry.

Also keep in mind if your emitters are over sized you will not need 170 awt. Even if you do you will not need those temps all season. Implement odr. All mod/cons com with this feature. 30% gain talked about is usually over an existing boiler that was probably oversized, and not the best efficiency to begin with.

So even if you get 92% efficiency75% of the heating season your still doing way better than a ci boiler.

Longevity, and maintenance intervals are getting far better than they were. Start every year see how the boiler fairs. The schedule could be lengthened out.

Gordy

Now is a Ci boiler cheaper yes.
Remember also there is a lot narrower selection to meet a heat loss with Ci also depending on brand. Some heat losses fall in a region where one Ci is to big , and the next size down is to small.

Another advantage to modulation. Filling those slots.

ChrisJ

Gordy can't resist a good banter.

njtommy

@ChrisJ I recently ripped out a Ci boiler that was rated at 150k btus two zones and very large pump in a 1600-1800sqft house.

Customer said his bills where $300 a month on average for NG. I installed an 80k mod con boiler and kept the two zones and installed the correct size pump. Customer called me and said his fist month heating bill was $100. Granted it's definitely not the coldest winter but that's a great drop in price per month. He stated he hasn't seen a heating bill that low in years.

So over pumping and short cycling does cost you a lot of money.

Gordy

And that is how the huge savings produced happen mostly.

ChrisJ

njtommy said:

@ChrisJ I recently ripped out a Ci boiler that was rated at 150k btus two zones and very large pump in a 1600-1800sqft house.



Customer said his bills where $300 a month on average for NG. I installed an 80k mod con boiler and kept the two zones and installed the correct size pump. Customer called me and said his fist month heating bill was $100. Granted it's definitely not the coldest winter but that's a great drop in price per month. He stated he hasn't seen a heating bill that low in years.



So over pumping and short cycling does cost you a lot of money.

No argument there.
What would a properly sized CI boiler and pump have resulted in tho?

Besides being a mild winter, NG prices have continued to drop. My gas bill went from $1800 a year to $900 a year recently between the prices dropping and the mild weather.

Gordy

1800 holy cow.

ChrisJ

Gordy said:

1800 holy cow.

Our neighbor was burning 5 large on heating oil to heat a slightly smaller house during those years.

Neighbor on the opposite side of us in a quite a bit smaller house with newer windows and forced air was spending a little more than us.


So, na, not holy cow.

Suzook

Let me throw a wrench into the mix....I have a slab foundation, and slab leaks are common. So far so good, but if I develop one, I will be adding a heat exchanger to my Central AC air handler, and using that for heat, and just abandon the fin. Does this sway it back to a ci?

bob eck

Check out the new Lochinvar Noble condensing combi boiler.

http://Lochinvar.com.s102530.gridserver.com/

Combi boiler with SS fire tube heat exchanger with brazed plate heat exchanger for domestic hot water.
This boiler has a 10 to 1 turndown. 110,000 BTU input turndown to 11,000 BTU

What about adding a buffer tank?

Suzook

> @bob eck said:
> Check out the new Lochinvar Noble condensing combi boiler.
>
> http://Lochinvar.com.s102530.gridserver.com/
>
> Combi boiler with SS fire tube heat exchanger with brazed plate heat exchanger for domestic hot water.
> This boiler has a 10 to 1 turndown. 110,000 BTU input turndown to 11,000 BTU
>
> What about adding a buffer tank?

That unit is $4k! My indirect HW heater and modcon is about $1200 after rebates.

bob eck

Where are you located at?

Suzook

> @bob eck said:
> Where are you located at?

Long island NY.

bob eck

What unit are you looking at using.

Suzook

> @bob eck said:
> What unit are you looking at using.

Burnham xc, or k2 firetube...leaning towards the xc for price.

ericmmff

What's with all the accounting?
I spend $6oo a month on beer .
The cheap stuff.
Set it and forget it.

ChrisJ

ericmmff said:

What's with all the accounting?

I spend $6oo a month on beer .

The cheap stuff.

Set it and forget it.

Wow,
I drink water and spend zero on beer.

Eric has a point.
We're not supposed to discuss cost on here. It's one of the very few rules they have.

$600 a month on beer though, wow.

Gordy

ChrisJ said:

ericmmff said:

What's with all the accounting?

I spend $6oo a month on beer .

The cheap stuff.

Set it and forget it.

Wow,
I drink water and spend zero on beer.

Eric has a point.
We're not supposed to discuss cost on here. It's one of the very few rules they have.

$600 a month on beer though, wow.

Maybe he has lots of friends.

You know the lyric." The fun never ends as long as I'm buyin"

Gordy

ChrisJ said:

Gordy said:

1800 holy cow.

Our neighbor was burning 5 large on heating oil to heat a slightly smaller house during those years.

Neighbor on the opposite side of us in a quite a bit smaller house with newer windows and forced air was spending a little more than us.


So, na, not holy cow.

you all need to do some envelope upgrades

Suzook

OK, let's take the $ out of equation. I posted I might eventually switch to a heat exchanger in my air handler in the future. Will that work better with a modcon, or ci?

Gordy

How old is the present system?

Suzook

Gordy said:

How old is the present system?

Its a 30 yr old 150k oil boiler in my laundry room. Wife wants the new out of the laundry room, and I don't blame her. We can use the extra space.
You mean the air handler? Its 3 yr old variable speed trane.

Gordy

The fintube piping in the concrete you are worried about failing. 30years.

You already have an airhandler? So why not switch now? Especially if it will make the wife happy.

Gordy

Depends on what they used for piping. M, or L, or iron.

Gordy

Also if you are looking to gain space I think you answered your own question on which type of boiler.

As far as abandoning the fintube. I would wait until the day. You will still get 85% with elevated awt.

So the question you need to ask yourself is.

Is it worth the extra money of a mod/con to gain the space?
Is it worth the maintenance to gain the space?
Happy wife happy life?

Suzook

Gordy said:

The fintube piping in the concrete you are worried about failing. 30years.

You already have an airhandler? So why not switch now? Especially if it will make the wife happy.

Piping in slab is 50 yrs old. I don't want to switch until necessary, as I'm partial to hw heat. Not a fan of forced air, but will deal with it as a last resort.

Gordy

Crap shoot. Could last another 50, or leak tomorrow. Anybody's guess. Depends on the soils, and concrete mix. Specifically fly ash.

njtommy

If you convert to hydroair you can design coil design 140 supply water temp max and also get a lager water temp drop acrossed piping. So you can condense all winter.

Depending on where your supply grills are and if your slab on grade you may not feel as comfortable as having baseboard. Ive noticed this at several houses I've been too. If the grills are in the ceiling and your sitting down you can get a little chilly. The moment you stand up you can feel the heat difference.

Suzook

> @njtommy said:
> If you convert to hydroair you can design coil design 140 supply water temp max and also get a lager water temp drop acrossed piping. So you can condense all winter.
>
> Depending on where your supply grills are and if your slab on grade you may not feel as comfortable as having baseboard. Ive noticed this at several houses I've been too. If the grills are in the ceiling and your sitting down you can get a little chilly. The moment you stand up you can feel the heat difference.
>
>
>
They are ceiling mounted. Forced hot air is a last resort if the fin fails. But it sounds like the modcon will work well with the hot air. I think I will just get the modcon.

ChrisJ

I'm with you on that, keep the fin until you have to do something. Maybe you never will.

I still don't like the idea of hydroair


You're basically using hot water driven forced air. Yes, I know, it's lower temps, but you're getting rid of all of your radiant heating which is the best part.


If you're just going to go and do hydroair then just get a 95%+ AFUE forced air furnace and be done with it.

Can't believe I just typed that. I must be getting sick or something.

Gordy

I think I would throw down some Roth panels, and do radiant floors when the system bites the dust before hydro air for the sake of comfort. It is an option. A more expensive one though.

NY_Rob

Suzook said:

Burnham has a zone control that adjusts the firing rate to compensate for small zones that won't condense properly. Thoughts?

Can you explain it's operation or provide a link?

Two things that can not be changed:
1) An 80K BTU boiler with a 5:1 turndown can only modulate down to 16K BTU output.
2) At Average Water Temp. of 120F, 50' of fintube can only dissipate 10,500BTU's.

-The low firing limit of 16K BTU's for that boiler can not be changed.

-The 50' length of the zone can not be changed..... unless the boiler opens another zone valve an uses that zone as a buffer.... temporarily making a much larger zone. It would have to work in unison with the outdoor reset sensor and curve- you would have to set it up where anytime the outdoor temp goes above 45F for instance- any call for heat from the short zone would cause both zone valves to open.

Suzook

> @NY_Rob said:
> Burnham has a zone control that adjusts the firing rate to compensate for small zones that won't condense properly. Thoughts?
>
> Can you explain it's operation or provide a link?
>
> Two things that can not be changed:
> 1) An 80K BTU boiler with a 5:1 turndown can only modulate down to 16K BTU output.
> 2) At Average Water Temp. of 120F, 50' of fintube can only dissipate 10,500BTU's.
>
> -The low firing limit of 16K BTU's for that boiler can not be changed.
>
> -The 50' length of the zone can not be changed..... unless the boiler opens another zone valve an uses that zone as a buffer.... temporarily making one long zone. It would have to work in unison with the outdoor reset sensor and curve- you would have to set it up where anytime the outdoor temp goes above 45F for instance- any call for heat from the short zone would cause both zone valves to open.

http://www.usboiler.net/control-system/sage2-1-boiler-control-system.html

BTW...Net output of unit is 64k...That matter?

NY_Rob

^ looks like that control system will allow you to set a max fire rate per zone. So, it will hold off hitting high limit for a bit longer vs. firing at 100% then modulating down, but once you hit high limit- it has no choice but to cease firing and re-fire on low limit. The boiler can only fire down to 16K BTU's and the zone can only radiate 10.5K BTU's (at 120F), short cycling is inevitable. It will only get worse once outdoor temps climb and AWT=110F or lower.

One thing to consider... once spring temps hit- just leave the long zone's zone valve open all the time manually. That way it will get heat when called for, and it will provide a buffer for the small zone when it's calling for heat.

Suzook

NY_Rob said:

^ looks like that control system will allow you to set a max fire rate per zone. So, it will hold off hitting high limit for a bit longer vs. firing at 100% then modulating down, but once you hit high limit- it has no choice but to cease firing and re-fire on low limit. The boiler can only fire down to 16K BTU's and the zone can only radiate 10.5K BTU's (at 120F), short cycling is inevitable. It will only get worse once outdoor temps climb and AWT=110F or lower.

One thing to consider... once spring temps hit- just leave the long zone's zone valve open all the time manually. That way it will get heat when called for, and it will provide a buffer for the small zone when it's calling for heat.

How about this guy??? It does 10:1 getting my 2nd zone condensing most of the time???
http://www.htproducts.com/UFT-Boiler.html

njtommy

I think everyone will agree that HTP makes a good quality product. But it comes down to the installer and making sure it's installed and set up properly.

The nice part about the UTF is it's a bit less money in pumps and piping cause you don't have to install a primary secondary pipeing arrangement.

Have you started interviewing contractors yet?

Suzook

njtommy said:

I think everyone will agree that HTP makes a good quality product. But it comes down to the installer and making sure it's installed and set up properly.



The nice part about the UTF is it's a bit less money in pumps and piping cause you don't have to install a primary secondary pipeing arrangement.



Have you started interviewing contractors yet?

My buddy is a licensed plumber.

NY_Rob

Suzook said:

How about this guy??? It does 10:1 getting my 2nd zone condensing most of the time???
http://www.htproducts.com/UFT-Boiler.html

80K BTU's with a 10:1 turndown gets you down to 8K BTU's at minimum fire. As long as your AWT doesn't go below 110F you should be fine with that boiler as 50' of fintube at 110F can radiate 8'000 BTU's
There are always situations where you may short cycle due to a cold night with fast rise in outdoor temp in the morning, etc... but you're about as close to ideal w/that boiler as you can get with a 50' zone.

That particular boiler has a "step modulation" feature that lets you "step" up to full fire rate in six steps at 1 min. intervals if enabled vs. just starting at 100% fire and modulating down when nearing CH setpoint. It definitely helps prevent short cycling during shoulder seasons. It also has a limit setting for spaceheating where you can limit max fire down to 50% of capacity or anything in between 50% and 100% of rated capacity depending on your heatloss.
If you set your ODR to never supply over 150F water, your 150' of fintube could dissipate 57K BTU's so you could limit the boiler to 70% and it would not be able to exceed 56K BTU's output. It's just another way to prevent the boiler from hitting high limit too quickly.

A few of us on this forum have the HTP UFT-80W, it's been working out well for most of us.

As njtommy mentioned, it's plumbed as primary, so less piping and one less pump too.

Blackman is a distributor for HTP on Long Island.

Suzook

NY_Rob said:

Suzook said:

How about this guy??? It does 10:1 getting my 2nd zone condensing most of the time???
http://www.htproducts.com/UFT-Boiler.html

80K BTU's with a 10:1 turndown gets you down to 8K BTU's at minimum fire. As long as your AWT doesn't go below 110F you should be fine with that boiler as 50' of fintube at 110F can radiate 8'000 BTU's
There are always situations where you may short cycle due to a cold night with fast rise in outdoor temp in the morning, etc... but you're about as close to ideal w/that boiler as you can get with a 50' zone.

That particular boiler has a "step modulation" feature that lets you "step" up to full fire rate in six steps at 1 min. intervals if enabled vs. just starting at 100% fire and modulating down when nearing CH setpoint. It definitely helps prevent short cycling during shoulder seasons. It also has a limit setting for spaceheating where you can limit max fire down to 50% of capacity or anything in between 50% and 100% of rated capacity depending on your heatloss.
If you set your ODR to never supply over 150F water, your 150' of fintube could dissipate 57K BTU's so you could limit the boiler to 70% and it would not be able to exceed 56K BTU's output. It's just another way to prevent the boiler from hitting high limit too quickly.

A few of us on this forum have the HTP UFT-80W, it's been working out well for most of us.

As njtommy mentioned, it's plumbed as primary, so less piping and one less pump too.

Blackman is a distributor for HTP on Long Island.

Thanks for the info. I am assuming a distributor carries parts, or can get them quickly? Just concerned with issues getting parts in case of breakdown. I can get the Westinghouse version online for a very good price...thoughts? They are authorized seller. It looks like its cheaper too.

Gordy

Just remember you get what you pay for. There is a reason why other units cost more. Even with in their own brand name. Usually that is in the control capabilities.

For the price point the uft is a nice option. Remember that fintube does not have much mass. Which means quick emitter heat up. Which means elevated return temps, and shut down on HL. Even with 8k low end you can expect cycling on milder heating days. The step modulation, and modulation down firing feature will help curb this tendency. Just so you understand how those features are used.