UFT 80 question

aldefed

Hello guys,
I have a project where I am installing a UFT 80 in a garage. The heatloss is 24000 BTU at design. The plan is to keep the garage at about 50 degrees with the radiant floor. When someone wants to go and use the garage and warm it up more, I am installing a Modine hydronic heater unit (around 50,000 BTU). This will be piped as a DHW load so I can run a higher water temperature through the Modine. I will use an Alpha2 for the radiant (direct piped) and a 15-58 for the Modine. In looking at the HTP manual, they have the heating loop pumped out of the boiler source and the DHW loop pumped into the boiler return. They show a swing check valve on the return of the heating loop. If both pumps have integrated check valves is this swing check needed?

Thanks,
Al

NY_Rob

If you're referring to figure 9 in the current install manual... that particular installation shows a IFC on the DHW pump, but no IFC installed on the CH pumps... so in that case you would need the discrete IFC. If you're installing an Alpha2 for CH with the built-in IFC, you can forego the discrete IFC.

Sounds like an interesting project.
A few of us here have the UFT-80W- excellent boiler!
We have a pretty good knowledge base regarding that boiler... ask lots of questions!

aldefed

Yes, I have been watching all the discussions on this boiler. I pretty much am going to use all the suggestions I have seen over the various threads and have been keeping notes on the various components suggested. This is actually a pretty simple project. I used closed cell spray foam under and along the sides of the slab, spray foam above the ceiling and fiberglass in the walls. 1 radiant manifold with (6) 200' loops in the floor. The modine will be used to quickly bring the garage up to a higher temp when in use and the radiant floor will keep the space at 50 degrees when not in use. By using the DHW for the modine, I can post purge long enough to remove the higher temp water before it switches back to low temperature for the floor.

aldefed

In looking at my figure 9 manual (just downloaded it yesterday), it does show flow checks at the pumps.

NY_Rob

Odd... my Fig. 9 shows "circulators" and "DHW Pump with IFC". The CH circulators in my Fig. 9 don't indicate "with IFC"...

aldefed

If you look at the pump symbol and compare it to the legend in figure 7, that symbol means it has a flow check in it.

NY_Rob

^ gotcha!
Odd how HTP indicates "with IFC" sometimes in their diagrams and other times they rely on the actual drawing to represent the IFC?

One thing that you may want to consider is rather than using both the top and bottom supply connection- just use one (doesn't matter if it's top or bottom) and run that through the Dirtmag/air sep. and then branch out from there to the radiant and radiators.

This particular boiler has some minor issues with entrained air, if you use both top and bottom supply connections you're only running water through the Dirtmag when the one circuit is active rather than running all the water through the Dirtmag/air sep. all the time.

I followed the factory diagram and eventually ended up re-piping to a single supply, another member here also had to re-pipe after following the factory diagram because he couldn't get the entrained air out either.

aldefed

So basically from supply of boiler, dirt/air seperator, expansion tank, then a T going to each pump?

NY_Rob

Yes, correct....

Here's how I ended up re-piping mine for a single supply (which quickly addresses the air issue):

aldefed

I see you used separate flow checks. Why did you choose that instead of the integrated ones?

NY_Rob

One of them (the 15-58) was back-flowing within 6months of install and the one on the Alpha was a little loud, so I pro-actively replaced both with full size 1" flow-checks.
The inline flow checks are silent and low resistance compared to the tiny ones built into the pumps.

NY_Rob

Another thing to keep in mind is with a garage install intake and exhaust runs can be extremely short compared to a basement install.
There is actually a minimum combined equivalent vent length spec for the UFT-80W. IIRC it's 10' for 2" pipe, for 3" pipe the minimum equivalent run length is even longer.
So if you have very short vent runs- stay with 2" pipe.

aldefed

Thanks. Yes I noticed that about the vent, I will need to use 2". Any concerns with using HTP's concentric vent?

NY_Rob

Not many here have good things to say about concentric venting. They seem problematic. If you can find the connectors, etc... you need in 2" CPCV and forgo the concentric that would be great!
All CPVC... no worries at that point.

steamedchicago

NY_Rob said:

^ gotcha!


This particular boiler has some minor issues with entrained air, if you use both top and bottom supply connections you're only running water through the Dirtmag when the one circuit is active rather than running all the water through the Dirtmag/air sep. all the time.

Is there a reason (other than cost and easy of piping) to not use two sir separators, one on each supply outlet?

Gordy

No need for that when properly piped.

NY_Rob

Decent multi-function air/dirt/mag sep for mod-con's are $200+, why use two when you can use one with zero ill effects on operation.

You can only run one circuit (CH or DHW) at a time anyway... so you only need one air sep... just pipe it so you branch out to CH or DHW after the air sep.

I know five people with the UFT-80W boiler, all (including myself) have originally piped according to the HTP I&O manual... all five of us have had air problems in the DHW loop because of the exclusion of the air sep. in the factory illustration.
The easy fix is pipe a single supply to the air sep. then branch out from there. It works perfectly when piped that way.