hydronic forced air - recommended boiler temp?

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Old 01-21-13, 07:56 AM
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hydronic forced air - recommended boiler temp?

Not sure if this is the right forum, but needed to ask. I've got my home HVAC mostly figured out now, it's a high-velocity system with heat supplied by the water boiler. Earlier I was having issues with the house taking a long time to heat, but after opening back up some vents and turning up the water temperature, it seems to be behaving better.

So my question is, how hight are we supposed to set the water temperature? I know normally it's recommended we don't turn it higher than 120F, but since we use it to heat the house it's supposed to be set higher. The water tank does have a mixing valve already, so the tank temperature doesn't affect what comes out of the taps too much, but I wanted to know what the recommended temperature would be for most efficient heating of the house, without wasting energy by setting it too high or causing excessive wear on the boiler.

Thoughts? Thanks in advance!
 
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Old 01-21-13, 09:39 AM
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after opening back up some vents and turning up the water temperature, it seems to be behaving better.
What 'vents' have you opened? air vents? is that what you mean?

I know normally it's recommended we don't turn it higher than 120F, but since we use it to heat the house it's supposed to be set higher
Do I understand correctly that your home is using a domestic hot water heater to supply heated water to a 'hydro-air' system?

I don't think you will have any joy with this...

Hydro-air requires some fairly hot water, hotter than 120... probably even hotter than 140...

Please explain more details.

One thing that we would like to know is the 'make and model' of the 'boiler'...
 
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Old 01-21-13, 02:36 PM
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What 'vents' have you opened? air vents? is that what you mean?
Yes, I meant a number of the "out" vents in the house had been closed, but I've seen on here that that's apparently a bad idea, even in unused rooms as it could cause flow and pressure issues, so they've been re-opened.

Do I understand correctly that your home is using a domestic hot water heater to supply heated water to a 'hydro-air' system?

Yes, that's it exactly. I'm not sure what the correct term for it is, it seems to be a system that's hard to google for, and not recommended by anyone, but hey that's what the house came with so just trying to work with it =)

I don't have the model of the hot water heater off hand (sorry I kept calling it a boiler), will try get it tonight. I did look up the temperature control manual and it was previously set to 130F. That caused the air coming out of the vents to be lukewarm at best, so I adjusted it to 145F over the weekend. There was a drastic improvement in the speed the house came up to target temperatures, particularly since the outside weather was colder than the days prior. I just wanted to know whether this was "normal" practice, and how high should it be set, if there were any concerns other than excessive energy usage from setting it too high etc etc.

 
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Old 01-21-13, 03:35 PM
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Yeah, ya gotta work with what ya got! At least for the time being anyway.

The problem with using hot water heaters is that they have limited BTU output available, and you being north of the 49th, it gets pretty cold up there!

There really isn't much more that you can do at this point I'm afraid.

You've got the water heater about as hot as you dare, and what you get is what you get.

As long as your tempering valve for the domestic side is set to 120F you won't have any scalding burn issues... so that part is OK.

You might be able to get warmer air out of the vents if you turn the blower speed down (IF it's a multi-speed blower), but then you could well be back to where you started... yes, warmer air, but not as much of it, a wash usually.

Let me know the model when you get a chance...
 
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Old 01-21-13, 08:15 PM
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water heater model
State Premier Power Vent GP650YTVITCGA
50Gal tank
76000 BTU

controlled by a White Rodgers Intellivent

Is it safe to run it near the high end of the temperature settings? Figure I can turn it down in the summer when it won't be needed for heating the house.
 
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Old 01-21-13, 08:28 PM
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That's a good amount of BTU... maybe even enough...

As long as you are ABSOLUTELY CERTAIN of the working condition of the tempering valve, you can probably turn it up a bit more...

I'm looking now for the manual to see what State says about it.

Is there an ASME "H" marking on the unit? (check all labeling)

 
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Old 01-21-13, 08:36 PM
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So far I've found this:

• Hot and cold “side taps” allow Premier Power Vent to be used for “combination” systems for water heating plus space heating, radiant floor heating or other applications requiring a recirculating hot water loop
Which indicates that State seems to think it's OK for heating apps, but I haven't yet found anything that states what the highest operating temp is allowed to be.

I don't see the "H" marking on the list of certifications in the brochure...
 
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Old 01-21-13, 08:40 PM
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Found instruction manual, might want to download and print if you don't have it:

http://www.statewaterheaters.com/lit...197425-005.pdf

Haven't read it yet...
 
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Old 01-21-13, 08:45 PM
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I would like you to compare your installation to the diagrams in the manual...

Let us know if it's installed as directed by the manufacturer.
 
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Old 01-21-13, 09:01 PM
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I strongly advise that you read the entire manual.

I did not see anything in the manual that spoke of a maximum temp limit, but the control is adjustable up to 160°F

YES, this WILL MOST DEFINITELY use more fuel to run hotter, there is no way around that.

The coolest temp which will keep the home warm is what you want to do.
 
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Old 01-22-13, 06:24 AM
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wow, thanks for finding all of that!! Comparing the "typical installation" in the manual to my actual installation, they seem to have not used the dedicated heating system valves to connect to my air handler and instead connected the heating system to the nontempered water supply and return valves instead. Which I guess means that my dish washer and washing machine is having to work a little harder than they should!

Those dedicated heating system plugs are not used at all. Also I think the circulator is on the inlet side of the air handler rather than the outlet side.

Would any of this affect the efficacy of the heating system?
 
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Old 01-22-13, 04:41 PM
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Ya know, I will NEVER, EVER understand why installers don't read the durn manuals!

Sometimes I think they must believe that they are 'knee pads' to use when kneeling to hook something up in order to keep their Levis clean.

I mean, there MUST be a REASON that the manufacturer bothered to include the fittings in the design and include the piping information in the manual in the first place, right?

I suspect that in this case it's a matter of FLOW. I looked again at the manual to see what size the side plugs are. I suspect that they may be 1" and the piping to the air handler should also probably all be done in 1".

If they piped off tees on the supply and return for the domestic side, they probably ran all 3/4" which if you are trying to get more than 40K BTU out of the unit is not the best thing.

Did they at least install the CHECK VALVE as shown in the diagram?

The PUMP MAY HAVE a check valve installed... the model number should tell that.

The pump being on the 'other' side is not a show stopper.

Yes, the air handler will 'compete' for flow from the domestic piping.

If they had piped out the side as they were supposed to, they likely would have more flow, and less competition for flow from the domestic side.

That's a nice water heater... take care of it... follow the suggested maintenance as far as flushing the sediment and periodically having the anode rods inspected and/or replaced. It will last a LOT longer if you do this.
 
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Old 01-22-13, 04:45 PM
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Top Inlet and outlet connections: 3/4" male NPT
Circulation loop connections: 3/4" female NPT
Just found this info in the brochure... so I was wrong about the 1" side port side... but still, not installed 'correctly'...

Sure, it will still work, but why 'second guess' the manufacturer?
 
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Old 01-22-13, 05:54 PM
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hehehe you sound like me when I see deranged server or networking installations.

I actually don't think I see a check valve.

That's the entirety of the hardware between the untempered supply and return. The right side with the pump is on the supply side, the left is the return.

Pump looks like its made by Grundfos, but don't see a model number.

Thanks so much for all the help NJ!! Just by hand feeling the temperature of the return line vs. the supply line, I think turning up the boiler temp has helped considerably, the return line no longer feels barely lukewarm, so I think I may actually be able to turn the water temperature down a bit. Guess I should get a plumber to come connect the air handler to the proper fittings and maybe move the dishwasher and washer to the untempered supply instead of the mixed supply.
 
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Old 01-22-13, 08:18 PM
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If I'm not mistaken, that doesn't even look like 3/4" tubing... but pics are hard to tell sizes. That's not 1/2" tubing, is it? Should maybe be printed on it somewhere?

Guess I should get a plumber to come connect the air handler to the proper fittings and maybe move the dishwasher and washer to the untempered supply instead of the mixed supply.
If you are turning that heater up past 140, I don't know that you even want water that hot going to the either washer... the dish one probably has a heater in it, no? I guess you could turn that off if the water was already hot enough.

The pump MIGHT have a check valve in it already... it should be labeled so.
 
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Old 01-22-13, 08:37 PM
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Ah, was just thinking it's a waste of energy heating up water, cooling it back down, then heating it again for use in the dish washer. I should probably look up the manual for that too then first =)

Couldn't find anything that looked like a diameter number, so took a tape measure to the rubber hoses and they're 3/4" external diameter, so I guess they're 3/4" tubing? or does it go by internal diameter?

All I see on the pump is "Grundfos Nonsubmersible Circulation Pump"
the rest is hard to read. I think it says "Type: UP 15-42 BUC5" or BBC5. Actually must be BUC5, google seem to come up with the pump, but doesn't say anything about a check valve:
http://ca.grundfos.com/content/dam/G..._BUC7_0311.pdf
 
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