Design updates for ModCon Boiler in 100 year old high mass gravity system

PC7060

Selecting the DHW circulator to meet the 6-7 GPM flow from teh HTP UFT80 through the HTP SSU45 Indirect tank.

I've looking at a 3-Speed Circulator such as the Grundfos UPS15-58FC, however having some difficulty determining what speed selection is optimal since GPM varies with head.

The Pressure drop table on pg. 10 of the the "HTP SuperStor IO&M Manual lp-83" lists a head of 8.3 at 6GPM and 11.3 at 7GPM.

The recommended flow rate listed in HTP SuperStor IO&M Manual Part 2 "B. Performance and Sizing Guidelines" listed hed of 6-9 and a recommended GPM of 8 GPM for a 84000 Boiler size.

Based on this the mid level speed of the UPS15-58FC seem like the best option.

Does this seem reasonable? What is the "typical circulator used for this application?

PC7060

Reviewing Caleffi Mixing Valves at SupplyHouse.com. Preferred valave is the Press Union AngleMix Thermostatic Mixing Valve w/ Temperature Gauge. Question: Is the check valve required for DHW tank mounted mixing valves?

The Caleffi site has a tech note from 2016 which says check valve not required unless called out by local code authority but may be used to prevent thermal siphoning.

@hot_rod @mattmia2 & co. - What's your recommendation?

hot_rod

They can prevent cross flow if pressure is different on H&C. Water softener, tankless coils for example, and for thermosiphon.
Thermal drop can also be used to prevent thermosiphon.
The AngleMix is unique in that it can shut ports off 100%. Nice when using recirculating to prevent temperature creep

PC7060

thanks for information, Hot Rod. The check valve unit is $50 and figure I'd save the money if not required.

PC7060

Hi all,

The old boiler is out and have the boiler wall set up and ready for hardware.

Had few questions I wanted to run by group.

1. Reading the installation manual I see a configuration with two shutoff and two drain labeled purging valve. What’s the purpose of the purging valve and how are they used?

2. Drawing also shows the make up water input connection between the expansion tank and the main circulator. I thought the fill was supposed to be on other side of expansion tank to prevent the circulator drawing fresh water in from the supply regulator when the pump starts up

3. Drawing shows unions at all supply and return connections. Is this a common practice?

Thanks!

mattmia2

The air separator needs to be between the boiler outlet and the pump. the tank needs to be on the suction side of the pump. The prv is typically at the air separator and the tank but is less critical. The purge valves are so you can block the flow and force makeup water from the prv through the system and out a drain to force most of the air out without having to bleed it.

https://heatinghelp.com/systems-help-center/pumping-away-piping/

PC7060

Thanks for the information @mattmia2. 

I have my system configured with the pump on return side of boiler with DirtMag, expansion tank and water make up regulator T’d off main return line.  The Air vent is in factory position at top of boiler.  

Also based on recommendations from members here I’m adding a tee to pull the DHW hot water off the top end of the boiler rather than the bottom to prevent air entrainment during DHW only operations

PC7060

@mattmia2 - reread the link you provided along with the article below from Plumbing and Mechanical and now I get the advantage of placing the pump on top side of boiler. 

I’m reconfiguring my system per Dan’s drawing.  This Configuration also simplified mounting of the expansion tank which is a nice bonus! 

https://www.pmmag.com/articles/93285-pumping-away-from-what

PC7060

Is the check valve in the circulator required?  I’m asking because I’ve got a shutoff with drain on the hot out line of the boiler before the MBR and Grundfoss  Alpha2 per Dan’s diagram that @mattmia2 kindly pointed me too. 

 The Alpha came with a optional check valve which I’d prefer to leave out so I can bypass the boiler when I drain the supply side of the distribution system.  

The return side has shut off with drain just before the Dirt Mag so draining that side is no issue. 

Thanks!

mattmia2

Those aren't "check valves" per se, they are actually "flow checks". They provide some resistance to flow so that you will only get flow when the pump is on. They prevent ghost flow from a pump in another zone when the pump in the zone with the flow check is off. If you are doing all of your zoning by zone valves including the DHW(if you have zoning or DHW, I have lost track of your exact system design), then you don't need the flow check. If you are zoning by turning pumps on and off, then you need the integral flow check(IFC) in each pump outlet(or a separate flow check).

PC7060

@mattmia2 - succinct answer / thanks!

yes, I am using the pumps to control flow between the two “zones” and will make sure the IFC are installed. 

PC7060

Installation is going well and moving onto wiring along with installation of the vent lines.  Fresh air intake is complete but awaiting order for System 1738 Gas exhaust rated PVC. 

that brings me to my two questions. 
1. What gauge and or type of wire do you recommend to connect the pumps to the boiler control board?  120v pumps but low amperage and standard Romex is overkill 

2. anyone know of a source of supply  for System 1738 pipe and couplers in mid Atlantic / Virginia area?

thanks

mattmia2

Type MC cable and fittings is the easiest way to connect the pumps. Don't forget the anti-short bushing. It is still line voltage wiring that has the same rules for protection and support as any other line voltage wiring.

PC7060

Got it, thanks.  Easy enough to run and strap and have plenty of anti short bushing on hand too!

PC7060

I’m plumbing in the Caleffi Angle mixing valve to the HTP SSU tank and the delta angle between the hot and cold domestic connections are presenting a challenge. The SSU cold input is offset 10 degrees so not simple to make connection using straight pipe without several connections to adjust for position and angle.  

I’ve seen some tank mixers which use corrugated copper tubing (or stainless) to make the connection into the cold side of mixing valve. 

Is this common / industry acceptable way to make the connection?

mattmia2

I don't have a mixing valve (yet), but this is how I plumbed mine with crosses.
The pex was just a temporary install to get it installed quickly because the old tank started leaking before I was ready to install the new tank.

PC7060

Thanks for posting the pics @mattmia2.

I was able to make the connections using a street 45 and standard 45 along with a few 90. All of the Hydronic and DHW lines are complete. It was quite a packaging challenge given all the existing pipes and ductwork but I’m pretty happy with the end result.

Need to wire up the boiler and pumps which should be pretty straightforward.  Also need to run the exhaust vent lines once the System 1738 lines come in. The local Ferguson’s is working up the quote and will freight it in from North Carolina. 

Here’s some gratuitous pictures of the system....so far!

PC7060

@mattmia2 - did you replace a standard hot water heater with a indirect DHW tank? Is that  Uponor pex you used for domestic side?

i see you sweated all the connections for the copper. Tidy work. I tend to run too much solder into joint so my joints are not so pretty.  

Ironman

PC7060 said:

Installation is going well and moving onto wiring along with installation of the vent lines.  Fresh air intake is complete but awaiting order for System 1738 Gas exhaust rated PVC. 

that brings me to my two questions. 
1. What gauge and or type of wire do you recommend to connect the pumps to the boiler control board?  120v pumps but low amperage and standard Romex is overkill 

2. anyone know of a source of supply  for System 1738 pipe and couplers in mid Atlantic / Virginia area?

thanks

Where in VA are you?

PC7060

@Ironman - Hi Bob, I’m located in the Northern part of the state between Fairfax and Richmond. 

mattmia2

The indirect replaced a powered vent gas water heater that replaced a natural vent water heater when I bough the house about 20 years ago. Th blower on the powered vent was super loud and it had heat traps that would click multiple times every time you shut the water off as it bounced on the air chambers in the plumbing system.

All the pex is HE-PEX. The pex is just the feed to the prv at the boiler. I want to add an electric mixing valve to the outlet, add a bypass and some valves that lets me feed it from the top to flush it out the bottom of the tank, and move the feed for the humidifier and the prv before the shutoff for the water heater so i left extra pex on the feed to the prv.

I tend to use too much solder so it ends up on the ground wasted when i wipe it.

This is what it looks like currently:

Ironman

I'd recommend that you put Tee with a boiler gauge in the supply line coming out of the boiler. The one that comes on the bottom of it is almost impossible to view.

mattmia2

Oh, and don't do what i did which was got to a point where I thought this is costing enough already, i'm not going to put a union or isolation valve here. I especially wish i put isolation valves on the strainer in the glycol loop that goes out to the garage so i could clean that without having to re-pressurize it with a pump again.

I used the Caleffi prv with a gauge on it so I have pressure there and if I recall the boiler shows supply temp on the front. that gauge is useless unless you have it in a boiler room up on a wall with 10' ceilings.

PC7060

@Ironman - You must be a mind reader, I was looking at how to do that precise update. By tee, do you mean a iron tee before it transitions to copper?  I was considering cutting in to the horizontal run just past the first 90 and crimping in a press tee with FPT take off. 

BTW, You are correct, that gauge on the bottom side of the UFT is in a crazy awkward position

PC7060

@mattmia2 - Yeah I missed the boat on those caleffi pressure regulator valve with integrated shut off and gauge. I used a Watts regulator and put a ball valve shut off in the front end.   I had planned to watch the Coffee with Caleffi briefing on bringing up systems but missed it live week or so ago. I finally watched it on YouTube today and was very annoyed that I hadn’t put one of those units in.  I’m seriously thinking of adding one in right now actually and just writing off the Watts regulator

mattmia2

Can do it in copper or iron, just get a tridicator with a 1/4" npt fitting and make sure you have enough depth for the stem that reads temp.

Not the best pic, but this is how I did it on the loop that goes out to the garage.

PC7060

nice!

Ironman

PC7060 said:

@Ironman - You must be a mind reader, I was looking at how to do that precise update. By tee, do you mean a iron tee before it transitions to copper?  I was considering cutting in to the horizontal run just past the first 90 and crimping in a press tee with FPT take off. 

BTW, You are correct, that gauge on the bottom side of the UFT is in a crazy awkward position

Whichever way is easier for you. The gauge is 1/4” NPT.

PC7060

Variety of gauges at supply house and amazon. Bluefin seems to have the most readable display. Most of pressure scale have limited marking and range of 0-70 which can make it challenging to get a quick reading when the range of intersect is between 10-20.

Reviews are all over the place on the Bluefin; any recommendation on a reliable gauge?

The gauge that @mattmia2 used has great marking but have been unable to source it.

mattmia2

i got it from supplyhouse.com about 2 years ago. I seem to recall it was a lot harder to pick a gauge than it seemed it should have been.

PC7060

Thanks for the information. I see it is discontinued there but can order from pump products; listed under "Boshart" .

Edit: found the 3" version with 1/2 MPT fitting on Supply house.
https://www.supplyhouse.com/Boshart-TR30-CB2S-60-250-1-2-NPT-3-Face-Temperature-Pressure-Gauge-Short-Tridicator

Ironman

You may wanna pick another brand. Both reviews on that one said that it leaked when installed.

PC7060

@Irontom - Bummer.  How hard can it be to make a good gauge? All the gauges seem ridiculously cheap. Should be able to find a high-quality one for $30 or $40

PC7060

@mattmia2 I used a Caleffi Angle mixer. Took a bit of planning to pipes routed to match orientation but it came out great. 

PC7060

Dropped the MII gauage and have a Caleffi NA503040 (~$20) in the cart. No reviews but the other Caleffi products I've purchase have been good quality

mattmia2

a caleffi gauge will be fine. i didn't have a problem with any of the 3 super cheap gauges i bought, but who knows. I bought 1 tridicator and 2 pressure gauges, one to be able to verify that the glycol system had pressure from the garage and one larger face gauge for pressure testing.

PC7060

Wiring is complete and am currently going through the installer configuration settings. Most items I am leaving at defaults but had a couple questions on Boost mode and Anti--Cycle time:

HTP UFT IOM page 51
What is the intended purpose for Boost mode?
----
9:bt
Boost Function:
When Outdoor Temperature Mode is used, Boost Function increases the CH set point temperature by the Boost Degree temperature at time intervals (Boost Interval). Boost continues until the boiler reaches the maximum supply temperature set point based on the outdoor reset curve. The boiler will return to normal operation after the thermostat is satisfied.
Range: 0 - 120 min

-Boost Degree:
Sets the temperature added to the boiler target set point based on the Outdoor
Temperature Mode reset curve. Range: 5 - 15F Default: 10F

-Boost Interval:
Sets the interval time when the boiler will increase the temperature by the Boost Degree. Ex: Initial Boost: 10F. After 20 MIN Interval: Boost will increase CH set point temperature another 10F. After another 20 MIN Interval: Boost will increase CH set point temperature another 10F. This will continue until the boiler reaches the maximum supply temperature set point based on the outdoor reset curve, or until the thermostat is satisfied.
Range: 0 - 120 MIN Default: 20 MIN

----
The default Anti-cycling time is minimal, under what conditions would adjust this time up?
16: Ft CH Anti-cycling time: Default 1 minute
----

Jamie Hall

Way back up there somewhere it was mentioned that there was an existing compression tank, 40 gallons, mounted on the ceiling. What's wrong with it? Why would you want to replace it with a bladder type expansion tank which, if you are lucky, might be big enough and might even last half as long, if that?

mattmia2

The anti cycling time is if you have a small load that calls and is satisfied quickly. It waits some period of time before firing the boiler again. There is also an adjustment for the difference between the on and off of a heat call, how far the water temp drops before it fires the burner again. Both these settings can be used in a system where the minimum load(for example is only one or 2 small zones are calling or it is warm out and the heat loss is low) is less than the lowest modulation of the burner to make it run longer and less frequent burner cycles.

The boost function is to allow it to recover more quickly from a setback or cover a condition such as high wind or opening doors where the demand exceeds the reset curve. Of course if you have the reset curve right it should run almost continuously and the boiler has no way to know if the reason the heat call is long is because the load is matched or because it isn't keeping up.

PC7060

Jamie Hall said:

Way back up there somewhere it was mentioned that there was an existing compression tank, 40 gallons, mounted on the ceiling. What's wrong with it? Why would you want to replace it with a bladder type expansion tank which, if you are lucky, might be big enough and might even last half as long, if that?

Jamie - primary reason is space claim associated with the huge Thrush valve and the huge pipe connecting it to the main line.