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Zman

Zman

Joined on January 19, 2012

Last Post on July 24, 2014

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Ice Rink and Snow Melt

@ January 28, 2012 5:44 PM in Ice Rink and Snow Melt

I recently toured the mechanical rooms at a couple local ice rinks. Both had a compressor room to keep the ice frozen. Outside was a cooling tower to dissipate the heat produced by the process.
I both cases there was a large boiler room right next door. The boilers were heating DHW and providing heat for the exterior snow melt.
It seemed crazy to me that they were removing heat from the ice, only to dump it, then firing boilers to melt ice outside.
Has anyone tried using  outside slabs as the "dump" for the compressors?Even if the slabs just "idled" and the boilers fired if needed, the energy saving would be big.

The key is Mass and Differential

@ January 28, 2012 5:28 PM in Need about 18,000 btu's to heat small apartment any ideas.

I don't know where the BTU numbers for humans and dogs are coming from. I have always figured 300-600 per person depending on the level of activity.
The other 2 variables in determining the cycle length is the mass
(usually determined by the volume of the water) and the differential in
the boiler cycle at low fire. Many mod/cons will automatically increase
the differential at low fire in order to prevent short cycle. Also look
at the water volume of the boiler. Firetube designs usually have more
volume. In the event you can't come up with enough volume, a buffer tank
will solve the problem. I am assuming 18,000 is your design load on the coldest day. That being the case I would look at the cycle length on a "typical" day. If you system  can unload 10,000 Btu's on a typical day and is producing 20,000 btu's at low fire you are going to be producing 10,000 Btu's extra.If you look at a boiler system that has 10 gallons of water that runs at a 20 degree differential this is what it will do with the extra 10,000 btu's

10(gallons) x 8.33 (weight of one gallon) x 20 (degree differential) =1666 Btu's the system can "store".

10,000 Btu/Hr is 166 Btu/minute. This system would have a cycle length of 10 minutes 1,666/166=10

Not bad!

Don't worry about cycling on DHW. You should have plenty of storage to prevent that.

Just figure system water and differential and voila.

Picture

@ January 28, 2012 9:26 AM in Cirualation pump

A picture would help

Narrow it down

@ January 27, 2012 10:28 AM in radiant heat loss because of pex placement?

I have to agree with Gordon.You have to narrow down your problem. You have to know for sure that you have good flow in the correct direction and adequate supply temp. Never assume that because you "believe" the water is going the right way, that it is. By the same token, just because one gauge in one location is indicating a certain temp that the whole system is that temp. Measure it! Once you are absolutely positive that  you have flow and temp then start looking at the mixing blocks. I think 190 degree water for troubleshooting is fine. Eventually I would like to see either no mixing blocks or a boiler curve set slightly above the highest temp block curve. Unless you can get into this troubleshooting mind set you are going to continue chasing your tail.

setpoint controller

@ January 27, 2012 12:11 AM in Honeywell Aquastat - how to remove from tank?

I had a similar problem recently. I used a tekmar 150 setpoint control. You can mount it wherever you want and stick the sensor in the well. I works slick.You can also set the differential to get the boiler cycles dialed in.
Oh, a lot of these have a little set screw on the side of the well you need to loosen to remove the controller.

Nice spreadsheet

@ January 26, 2012 11:07 PM in Oil vs NG

Here is a nice spreadsheet for comparing energy sources www.eia.gov/neic/experts/heatcalc.xls

Only the inner part was 439

@ January 26, 2012 5:54 PM in Infloor radiant heating boiler recommendation

Only the inner part was 439. Now the whole thing is.I spent quite a bit of time talking with the engineer. The new control is super user friendly and visual. It will control 4 pumps and 2 different heating curves.It will also cascade multiple boilers automatically. I believe they have made great improvements on the best boiler on the market.

What is the pressure?

@ January 26, 2012 1:30 PM in water pressure from city

If you measure the city pressure and it is less than 20 psi this may be the problem.
I believe the mascot has a high head loss exchanger. If you are pumping out of it instead of into it I think that is likely your problem.

Arrow on the casting

@ January 26, 2012 11:32 AM in radiant heat loss because of pex placement?

It is possible they turned the motor when they installed the pump. if it is pointed down you are OK if it is up it is incorrect

Backward

@ January 26, 2012 11:24 AM in radiant heat loss because of pex placement?

Take a close look at page 2 and 15 of the manual. Then look at the arrow stamped on the grudfos pump. I am certain they are backwards. I live in house with tubing place to deep and with inadequate insulation underneath. I do have the correct carpet padding. I need 130 degree water on the cold design day to make it work. I have also done the the calcs in the textbooks and come to the same conclusion.

Electric or steam?

@ January 26, 2012 11:11 AM in one room radiant...

If you had the tile removed I would say electric mats. I do not know of an electric product that will install from below, but it may exist. You might try posting this in steam see  if those clever guys have a way to use the return water for hydronic infloor with aluminum plates

Firetube HX

@ January 26, 2012 10:57 AM in Infloor radiant heating boiler recommendation

I just got back from AHR. There have been been some interesting developments with exchangers. The company that used to make Triangle tubes exchangers is now selling it to other companies. This is why we are seeing so many new firetubes. Triangle tube has switched suppliers and now has a firetube similar to the old model but with better stainless, welds, and more even heat transfer. They are also making an 80# 399 and plan to make bigger boilers.The new trimax controller is unbelievable. The good news is that triangle tube got even better, if you want to spend the money. And many other companies now have a very nice firetube.

2 degree differential

@ January 26, 2012 10:48 AM in Frequent heater cycling

It sound like you have plenty of mass. A 2 degree diff is very tight for radiant. as far as the floor goes you won't notice a 20 degree diff. If you are running an open system (arg) you will notice it on the dom hot water side . the solution to this would be to install a thermostatic mixing valve on the DHW outlet. and raise the boiler diff.

How much passive?

@ January 26, 2012 10:39 AM in Gypcrete, Warmboard, Quik Trak... Which should I choose

I think the first question should be, how much passive do you get?High mass systems with tons of passive are a nightmare to control. They just overshoot and undershoot all day long. If you have passive go low mass.I would also recommend you keep it simple. If you do an accurate heat loss calc, then size the panels to meet the loads of each room based on the same supply temp, you can run the whole house off the boiler's built in reset curve and have a great simple system. Read "radiant precision" then only hire contractors who "get it"

Individual Control

@ January 26, 2012 10:27 AM in HELP!!! Seven zone hydronic conversion.

I this gennedy is right on. Put a thermostatic control valve on each radiator. If you system is in series you will have to use diversion tees or a similar product to maintain flows to the next heater. I believe callifee has a new product designed to integrate the new (to us) European low temp radiators to this kind of system. Ideally you would go low temp and put in a mod con. 

Piped backwards

@ January 26, 2012 9:37 AM in radiant heat loss because of pex placement?

It looks like the mixing blocks are piped backwards. If this is the case they are reusing much of the water they are supposed to be sending back to the boiler. I think this is the entire problem. Check the manual and the direction arrow on the main pump

Good

@ January 26, 2012 8:55 AM in radiant heat loss because of pex placement?

OK Good,
That eliminates some potential bottlenecks. I assume the out put to the lower level does not change regardless of what the upper level is doing.(the upper zone is not stealing all the heat) ?
Are you comfortable that the zone controller is set for the higher temp, and you are not getting it?
What I am saying is if you have good flow and high temp in the main pipe going past the  mixing block and you can't get the mixing block to inject that heat into the radiant loop,  it may be time to call taco and get some tech support. You may have a issue with the block

Check everything

@ January 26, 2012 12:44 AM in radiant heat loss because of pex placement?

I got to thinking on this. What kind of lunatic puts mixing blocks on a modcon boiler that already has outdoor reset? Both floors should be able to run at the same temp directly off the boiler. The boiler never fires hotter than it needs to and runs at optimal efficiency.Those mixing blocks are $1,000 bucks each!
 That being said I think you need to check everything. It looks like you have 1" main lines. That seems small for a 199K BTU boiler is the boiler a 200? What size is the boiler pump and what speed is it on? Are those 1/2" lines going into the blocks? Are the block sensors strapped to the correct pipe. Start  feeling the pipes. Are the pipe attached to the lower (undersized) headers at the same temp?
Your symptom is cold floors, the pex placement is not helping. There is something else going on.With those boiler settings you should be able to get the temp up. Is the boiler really getting that  hot? Does it have a gauge?

stagnant water

@ January 22, 2012 8:07 AM in Where to start?

I think professional design help was a good call. As far as you existing system my biggest concern is all the stagnant water that will never get hot enough to kill micro-organisms. That being said, there are thousands of systems like yours installed in the US. I would suggest doing your own research and perhaps testing your water.

Thermostatic bipass valve

@ January 21, 2012 12:24 AM in Indirect DHW with slightly undersized boiler

I think you are correct that the boiler will condense for a good part of the DHW cycle. I have a TT175 condensing boiler with a smart 60 tank. I have watched the return temps at startup and seen condensing temps for a considerable time under load (5 to 10 minutes). I my case I did it intentionally as the boiler is a mod/con. I think the simplest fix would be to install a thermostatic bipass valve on the boiler. This will assure hot return temps and have no effect on DHW production. I think it is great that you are thinking of this. Most folks would not have paid attention to a detail like this.

Can You Increase Pressure?

@ January 20, 2012 11:56 PM in tankless gas water heater question

I am assuming you have a 1/4lb system. How about going to 1/2lb and  adding a regulator at each appliance.

Looking for more info

@ January 20, 2012 9:19 PM in Honeywell XL50 MMI

The controller was installed in the year 2000. It is connected to an old school modem. There have been staff changes in the maintenance department and no one knows anything about the system. What am I looking for to interface? I am very comfortable with boiler/HVAC settings but have no experience with this system.
Thank you in advance 
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