I'm a Mod/Con virgin

Mike T., Swampeast MO

The condensate is quite acidic and thus corrosive. Can eat some metals quite rapidly. Not good for septic systems and not allowed without neutralization in some? many? all? public sewer systems.

The condensate is neutralized by passing it through a base--quite finely crushed limestone and marble are commonly used. Manufactures make units--you can also make your own.

Billy March

which boiler should I use

I am currently doing a job consisting of all radiant heat. In the past,I have done alot of baseboard with maybe a minute amount of radiant. But this is my first entire house of radiant. I know that this would be a perfect opportuninty to use a modulating/condensing boiler but I'm still a virgin in this arena. Everything I know about mod/con boilers(which isn't alot)I have learned from hanging out on the wall. Another concern I have is the customers hot water demand. He lives by the beach and has a ton of people at his house during the summer months. I want to make sure he has an ample supply of hot water year round,but I do not want to shortchange him during the summer. I have been doing some research and I am leaning towards the weil-mclain ultra. The house has 3.5 baths and 2 kitchen sinks. There is about 3000 ft of pex-al-pex tubing throughout the 2 story house. The ultra 155 with a gold plus 80 indirect seem to be the way to go (I think). What do you think??? I am welcome to any suggestion !!!!!

[Deleted User]

GO FOR IT...

We were ALL modcon virgins at one point or another.

For me, I'll probably never go back unless forced to due to conditions beyond my control. The keys to success with ANY mod con boiler is to install it per the manufacturers instructions, and run them at as low a temperature as you can, for as long as you can.

This ain't your grampaws Buick any more. Don't even think about putting it in the same way you've been putting other boilers in. Its an invitation to failure.

Enjoy!

ME

PS, Don't forget to neutralize the condensate.

ME

hr

Put a number

on that DHW load. It could well be the bigger load.

Mo-Co's will require more maintenance than the old standing pilot block of iron, of bundle of finned copper

There is a lot more to setting one up properly, not nearly as forgiving as the atmospheric stuff.

Settle in on a brand and get thee to a factory training seminar. Much better than trial and error installing.

hot rod

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Billy March

condensate

Hey Mark.........What do mean neutalize the condensate. I was going to pipe it to the floor drain. No good?????

Billy March

If I buy a bag of marble chips and pass it thru them before it hits the sewer, would that suffice???

[Deleted User]

We use

a 5 gallon bucket filled with crushed marble or crushed lime stone. You want it to have a good amount of contact time to make sure it gets neutralized.

We typically introduce the condensate into the bottom, thru a platic pipe, then cut a tap into the top,side of the bucket, and pipe it in plastic to the floor drain. Some other folks here have come up with their own designs for neutralizers using 3" PVC DWV fittings that will fill the bill.

Some modcon manufacturers make their own, but I've found the 5 gallon bucket works fine. It may have to be replaced in a few years, but at the cost of buckets, I can afford that, and so can my customer. You WILL be back there seeing your custoemr, at least every 2 years for service.

These little boilers are like red headed step children with freckles. If you ignore them, they will go away:-)

You MUST pay attention to them, or they will end up being an expensive throw away boiler, as they are portrayed by the "other" type of boiler manufacturers. With good care, my gut tells me theyre going to last around 15 years, and by then, something else will be out that is better.

ME

Billy March

Thanks for the info Mark.

Darin Cook_2

Hey Billy

The GB 142 has a very nice feature of being able to derate the input btus on the heating side. So for example if you need 120,000 btu's on the domestic hw side but only 45,000 btu's on the heating side you can set up the boiler to do this by the mere push of a button. It is the only one out of all the mod-con boilers out there that do this to my knowledge. Alot of our new homes have a domestic hw load much larger than our heating loads (six bathrooms, Kohler shower tower and a big jacuzzi tub is one that comes to mind). The GB derating feature gives you alot of flexibility in matching your loads.

Hope this helps,Darin

Floyd

Just for the record....

the WM Ultra will do that also.... I have my 155 running flat out for DHW and limited to 90 something for the heating side. With the PC interface making changes is really easy. And it's really not that hard to make changes manually from the front of the boiler either.

Floyd

Constantin

Gentlemen,

Did we ever resolve whether "de-rating" a boiler for heating load vs. DHW shifted the actual firing range?

I remain under the impression that the possible firing range of the gas valves/blowers does not change, whether you tickle the electronics behind the boiler or not. That is, a boiler whose initial firing range was 25-100kBTU/h is not going to be able to modulate between 15-60K just because of an electronic adjustment? Instead, you'd electronically straight-jacket that boiler to modulate just between 25-60k, right?

I'm also unconvinced that sizing mod/con boilers to the DHW load makes sense in most scenarios. A large, well-insulated indirect can do a lot to cover many loads, as Siggys HDS program shows.

If the DHW loads are continuous, that is a different matter however. Situations where large loads can be expected to run continuously, mod/cons with very large modulation ranges like the Trinity 400 may be the best tool for the job. Or, you could split the DHW from the heating system altogether.

Lastly, considering how much energy the likes of a GFX system can recover, it would be a shame not to use them for all high-flow showers you encounter out there.

Dave Yates (PAH)

If you have

a local supplier who offers exceptional service - after the sale - and they stock replacement parts, I'd be inclined to take a very seruious look at whatever brand of mod-con's they stock. Do they support factory training? Will they (and the mfg) defray costs for training if you need to travel to the mfg's location?

As mentioned, they're going to need annual or every-other-year service to keep em purring like a kitten.

Condensate issues will become service issues in a few years for ones where it's not being treated.

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Trevor Baptista

If you do not neutralize the condensate is that very bad. The installer on my WM 230 has the condensate going to a condensate pump which pumps directly to my sewer line.

Darin Cook_2

Constantin

I'm curious how many of your customers have called you back when their 120 gallon jacuzzi tub could not be filled with hot water? How many of your installations have been for floor warming but also had to pick up the domestic hot water load? Sizing ANY boiler for the domestic hot water load is right IF that load is HIGHER than the heating load. Many times I have used smaller indirect tanks but run at a higher temp with a thermostatic mixing valve to gain more hot water output and kill any risk of legionella. But that does not work ALL the time. A GFX recovery system SOUNDS good untill that shower is not used all the time. How long for the recoup in cost?

The GB 142 can be derated untill the 30% mark. At that point it will run with no modulation.

I am not trying to beat up on you here, but sometimes more than meets the eye goes into some jobs. Sometimes facts and figures do not mean anything to someone who does not have what they want. If they are willing to pay for it, they will get it. Lastly it is not always about energy savings. If it was there would be no snowmelt systems, floor warming, heated shower walls, fog free dressing mirrors, or the like.

Darin

Constantin

Darin,

You know just as well as I do that I have had just one "customer" to date, i.e. my own home. I completely agree with you that the system loads of either service have to be analyzed, I said so myself further up. My observation that indirect tanks work for most people is based on the hundreds of millions of customers in the US who are happy with lower-input, lower recovery gas/electric water heaters.

Granted, you seem to work for a different set of customers than the "average" American home. Homes with very large DHW loads (like 120 gallon jacuzzis that fill at 10GPM and all that) probably benefit from a completely dedicated water heating system like the VWH399. That makes running out of water that much harder. Then there is the question of marginal cost/benefit of upsizing the indirect to cover pretty much any load vs. installing a dedicated DHW heating system. You guys have those numbers, I do not.

As for the GFX, I put mine on the main stack out of the house. That way ANY shower/fixture/etc. will pre-heat the incoming water heater water. I will start to measure the temperatures soon, so far there is a 40°F ΔT between the incoming water temperature and the water running down the drain stack. Should be some opportunity for recovery.

Your comment on the GB modulation adjustment makes me believe that you do not adjust the firing range when you change the electronic parameters. Instead, you seem to impose an artificial ceiling to the modulation range, the usefulness of which I presently cannot fathom.

Clearly, you take great care and pride in the systems you have designed and installed and my comments were not meant to criticize either aspect of your work. You obviously do a good job of keeping your high-end customers happy, otherwise they would not be coming back for more all the time. Cheers!

Solarstar

GFX

I love the gfx ..Have been using it since 1999. Paul