Too Many Choices

Rich Kontny_3

A very fine gentleman who I have done a great deal of plumbing work for has moved his boiler room project ahead. His hand was forced when the gas fired water heater sprung a leak.

I am looking for advice about components. It  has about 2000 sq ft of copper in floor and about 1200 sq ft heated with baseboard total heat load about 195,000 btu and adding a 60 gallon indirect water heater.

Have been given a material quote for two Presige 125,000 wall hung mod cons and a compatible 60 gallon indirect (Smart 60)  I would like to use Taco pumps and accessories.

My questions are as follows: with four in floor zones,three baseboard zones and the indirect should I be considering a hydraulic separator?? Any better choices than the Prestige???

The current in floor is piped reverse return with no mixer which creates about a 25 degree temp differential.

Any suggestions before I throw a price out to the owner????  



Thanks in advance

Rich Kontny

CMadatMe

My advice

Recalculate that heat loss. I don;t know what part fo the country you are in  but I'm in NY and we design for 0 and that load seems awful high compared to the sq footage you are giving. Even if I take the old fudge factor of 40btu sqft I wouldn't come up with that load. Boiler wise, I would take a look at Viessmanns new Vitodens 200. Would only need 1 boiler. Yes you would use a LLH (hydro seperator). But the boiler gives you the abilty to cut down adding other controls. The LLH also has a sensor in it that will talk to the boiler and promote condensing.

The other great feature is that the burner/gas vlv continually looks at incoming gas pressure and mixture and adjusts as those change keeping the boiler burning clean and at it's optimum efficiciency. Also, 2 yrs parts, limited lifetime on heat exchanger. No other wall hung in this country has these offerings in their boiler line. Period.

EricAune

Consider cascading two boilers

Consider the benefits of a two boiler system.  With outdoor reset and a mod/con you can better modulate down to smaller loads.  Couple this with redundancy and the potential for less wear with two boilers.



Perfect situation to utilize a hydraulic separator or buffer tank.

The Steam Whisperer (Formerly Boilerpro)

Not much sounds right

I agree, heat loads sound off the chart.  I just did a 1950's copper tube in slab radiant system in a home about that size with lots of glass area here in northern Illinois last fall (-4 F design)  and a single Prestige solo 110 with a 40 Smart handled the loads just fine.  ( I am not sure if it was a typo, but there is no Prestige 125).  The 110 replaced a 250,000 input Weil.   Radiant floor max out at about 35 btu/sq ft..any higher and the floor gets uncomfortable hot, so thats only a load of 70,000  and then at most 48,000 for the baseboard, and that is really heavy.  My own 1908  home only has  load of about 17 btu/sq ft with tons of windows at -4 design.  I was running a 90,000 input boilerat aboutg 78% efficiency and it still cycled in sub zero weather. 

It looks like the numbers need to be revisited.



Boilerpro

ScottE

Consider

In the interest of diclosure, I work for Boiler Buddy. That being said I believe this a perfect app for a Boiler Buddy. Will provide hydroseperation and provide mass to prevent short cycling



Scott

Paul Pollets

Choices

First, you should be aware that the copper-in-slab (early Levitt system) has a life expectancy of 50 years. When it leaks, the zone will have to be replaced with either a new radiant floor or wall panel rads.

Second, any modulating condensing boiler will be a good match, I prefer Viessmann, but to hook up an indirect tank, 3 way valve and motor actuator for the existing RFH and a BB zone, you'll need hydraulic separation. This is not a project where 2 boilers would be required.  Size the boiler to the load. I'd suggest that a 90K output is all you'll need.

Jean-David Beyer

copper tube in slab

I am a bit concerned about this, since I have copper tube in the slab to heat my downstairs, and this house was built in the very early 1950s. So I have 55 or a bit more years on it already.



It is my understanding that what causes the corrosion of the copper is the acidity of the fly ash (if any) in the concrete. So would not the lifetime of the copper tubing depend on just what the ingredients of the concrete were? And also the wall thickness of the orignial copper tubing? What if my concrete had sand and  small gravel in it instead of more acid ingredients? (I do not happen to know.)

Paul Pollets

Levitt systems

Type L soft copper was usually used. The concrete alkalyds will ultimately dissolve the tubing from the outside in. There's no way of telling how long it will last without destructive testing. You'll notice the water bill increases and the CW feed sweats, as the pinholes develop. Pressure test the zone yearly to 60psi.

Since you awoke Murphy, he may visit the system on the coldest Saturday night in January.

Jean-David Beyer

Leaking copper tubing in slab...

I do not think I have any leaking yet. When the new boiler was put in in May, I turned off the feedwater and watch the pressure gauge every day. It never went down until the temperature outside dropped from the low 90s to the low 60s. Then it dropped about the width of the pressure gauge pointer. It is still well over 10 PSI and less than 15 PSI. Dial a bit too small to read well. (I wondered about putting a 4" pressure gauge in there, but it may not be worth the trouble.) When heating season starts, I will turn on the feedwater until all the air gets out of the heating zones for a coupla weeks and then turn it off again and watch the pressure gauge some more.



I do have a McDonnell & Miller MM-238(H) Conductance Type Low Water Cut-Off in there, even though I did not ask for one. My contractor would have it no other way, and I would have wanted one anyway.

Paul Pollets

low water cutoffs

LWCO's are required by code in most states. No boiler should leave home without one!!

Rich Kontny_3

Thanks guys

We are in Wisconsin wit a design temp of -10.I will do a complete heat loss. I know the Viessman rep (who also reps Taco) here in Milwaukee. I simply do not do a great deal of systems anymore only about two a year. The new mod-cons and hydro-separators are relatively new concepts and I want to do this as up to date as possible. Currently I am schooling to become a certified RPZV tester which will compliment my skills also.

95% of my work the past 6 years has been plumbing with just a few hot water systems thrown my way.



Thanks again!

Jean-David Beyer

low water cutoffs...

I certainly agree, not that it matters much what I think, that all boilers except for a tea kettle holding under 1 1/2 quarts of water and an open spout, should have low water cutoffs. My historic GE boiler, on the other hand, had no pressure relief valve, no low water cutoff. It did have an operating thermostat and an overheat thermostat. These seem never to have failed. One safeguard, if you want to call it that, is that it had no backflow preventer on it either, so if it did start boiling, it would force the excess pressure back to the water company. I doubt they would have appreciated that, but that was in the early 1950s.

Piper

Look at Triangle Tube

Visseman still have the lousy Giagnni (sp?) high head heat exchangers. Not to mention the outrageous price tag.

Triangle Tube is a very solid product IMO.