Floor heat boiler questions

[OurTown]

I hate making these quizzes because I think it puts some people off but if you can answer any of these it would helpful.

1. The auto high limit and manual high limit aquastats are wired in series. The auto high limit is set to 165F and the manual is set to 150F. Are these settings backwards? Although we have not had any issues they seem reversed to me.

2. We have a slab stat that is set usually for about 42F and it works fine until it gets stupid cold out and then we have to turn it up a few to compensate. There is an override air stat that is set for 16F and states to never change it. What is that for and how is it integrated?

3. The system was originally pressurized but was changed to a non-pressurized system years ago by the previous owner (Super Wash) to supposedly avoid the yearly boiler certification costs. The boiler registration plate is missing. Should we go back to pressurized and what would it take to get a new plate and start yearly certifications?

4. The circ pump timer has been bypassed and runs all the time if the boiler switch is on. When turned on the flow switch must be coaxed a little bit to close the circuit. Is the flow switch bad or does it need a pressurized system to work properly? As long as the pump runs it stays in the closed position and when it is off it goes into the open position. If we get a long warm spell we might turn off the switch but have to remember to push the flow switch a bit when we turn it back on.

Our system does work okay but it would be nice to get it working the way it was designed. Plus I like learning all about these things from you guys.

 

[soapy]

Flow switches do get sticky and need to be replaced once in a while. I would start with a flow switch. I did not like a pressurized system since it can lead to diluted anitfreeze in the system. If you do go back to pressurized system by a unit that has a tank and pump so you can keep track of the antifreeze. I would not have a direct line from your water system to the boiler system. I would find a good local boiler guy to look at it and bring it up to par.

 

[OurTown]

It's a closed loop system and all they did was replace a plug in the top of the bladder tank with a vent pipe.

 

[JGinther]

1. yes it's backward.
2. Looks like you answered your own question. Sounds like it will take over the slabstat when it gets stupid cold and your slab stat is getting a false impression of floor temperature. Maybe the slab stat isn't in an ideal location to not get mislead by heat from long run times of the boiler or is in a place where shade or wind chill isn't a factor.
3. Their method saved money and hassle, as boilers that can't pressurize are not pressure vessels, so in some states that skirts the inspection requirement. You can call the state and ask them questions, but that's like calling your doctor.
4. This depends on a lot of things. Agree soapys response, and add that flow switches might have been over trimmed, used wrong spring (depends on type) , mounted in a bad place or direction, or pump not sized correctly, or bypass ( mixing valve if installed) not adjusted right for flow. And a lot of other dynamic possibilities. I don't think pressurizing will change the flow switch operation so long as air isn't getting entrained, but don't know how it is currently plumbed to know for sure.

 

[mjwalsh]

OurTown,

We actually had the paddle break more than once on some of our flow switches. Our solution was to reinforce at the base where the paddle was breaking with thin stainless flat. I think we cut using material from the spare paddles that came extra with the flow switches ... if I remember correctly.

 

[OurTown]

I'll look into replacing the flow switch but what about the pump running 24/7 for 5 months at a time?

 

[JGinther]

I thought you just led to them doing that because the flow switch needed manual help to get started. If you fix the flow switch, then make the t-stat run the pump timer like normal.

 

[OurTown]

I thought you just led to them doing that because the flow switch needed manual help to get started. If you fix the flow switch, then make the t-stat run the pump timer like normal.

Maybe the timer is bad and that is why they bypassed it or maybe the flow switch had been going bad for awhile. We had the same issue last year. (our first winter) I'm going to look at the way the flow switch is plumbed today so I can figure out what switch to buy. It has a McDonnell & Miller FS4-3-RPT and I'm not going to assume it is the correct one for our setup.

 

[copperglobe]

2. Super Wash has the slab stat and the air stat. Once the air temp gets down to the air stat temp the floor heat boiler is on constant- overrides the slab stat.

 

[OurTown]

2. Super Wash has the slab stat and the air stat. Once the air temp gets down to the air stat temp the floor heat boiler is on constant- overrides the slab stat.

Thanks. That makes sense.

 

[OurTown]

It looks like the flow switch is mounted in the heat exchanger on the right hand side of the boiler. Is this a good location? Copperglobe is yours like that?

 

[OurTown]

Another thing I forgot to ask is does anyone run a timer? Ours is set up to turn it off for the hours when we are supposedly less busy. To me that does seem like a good idea especially if it is really cold out.

 

[I.B. Washincars]

Take it from someone that's been sued for a slip and fall. They will look at every angle to make you the bad guy, so don't give them everything they will need to win by sacrificing their safety to be a cheap bass turd.

 

[OurTown]

Take it from someone that's been sued for a slip and fall. They will look at every angle to make you the bad guy, so don't give them everything they will need to win by sacrificing their safety to be a cheap bass turd.

Good point. It kinda goes with the other thread on salting the lot.

 

[mjwalsh]

Another thing I forgot to ask is does anyone run a timer? Ours is set up to turn it off for the hours when we are supposedly less busy. To me that does seem like a good idea especially if it is really cold out.

Since concrete holds heat pretty good ... we do somewhat the opposite. During the day when it is warmer our deicer tends not to run because our boiler controls are set to prioritize for our domestic hot water heating which includes both the wand bay water & the laundromat's washing machine warm & hot water. At night when we are closed & least busy is when ours gets caught up & then some to run less during the warmer day. We do have a timer for the circulating pump (daytime operation) that the engineer set up to make our Symmons Tempering Valve more accurate for our car wash domestic water going into car wash pumps for actual car washing purposes.

 

[GoBuckeyes]

Our washes always had a timer to shut the FH burner off overnight. The timers were set to turn off from 11pm and back on at 5am and had an airstat override that would negate the timer if it was too cold out, that was set at 15. The last wash we built we did not wire in a timer and we no longer use them where they are installed. It really depends on how well your system is put together and how your wash is situated . We’ve found that if the wind is blowing hard through the bays the FH has a hard time catching up when there is drifted snow in the bays or you get the few third shifters that come and use the wand to blow 4” of snow off their roof. In the morning there is a frozen ring of snow in that bay. When gas was $14/mcf maybe it was worth it but currently I’m not sure.

You really need to monitor how many minutes you’re boiler is fired during the hours you’re considering shutting it off and see what it costs you to run. Then you’d need to somehow figure how much extra it runs when it comes back on-line to get the slab up to temperature and deduct that from your possible savings. Once you do that then you can weigh the savings against the conditions of your floors in the morning and decide if it’s worth it.

 

[OurTown]

I went ahead and pulled the toggles that turn it on and off in the timer. With the catch up time when it's pretty cold the timer probably didn't save enough for the risk involved in a frozen bay.