Insulating Traps

RPK

According to some internet research I just did, it's okay to insulated F and Ts, but not recommended that thermostatic traps be insulated. I do some work for a church and we recently had asbestos abatement performed and replaced most of the traps and pneumatic control valves. The church staff (new building owners) are concerned about children getting burned by the exposed traps. What are some potential solutions for this issue? Would a PVC insulation fitting minus the insulation still allow the valve to cycle frequently enough to avoid risk of damaging the traps?

Sailah

The traps will be just as hot as the radiator. Insulating them won't help or harm performance. I suppose you could make the argument on an energy efficiency contention but I'd have a hard time buying it.

If the church is concerned for child safety perhaps they might send a note home with the parents asking them to not let the children touch the hot radiators?

Or perhaps a wooden cover?

I'm familiar with the custom ft covers and at low pressure the ROI is so far out unless you are getting someone else to pay for them it's money not well spent in my humble opinion.

Jamie Hall

@Sailah has nailed it -- first off, the problem is legal, not heating, and second place the radiators are just as much if not more of a hazard than the traps. If the legal eagles associated with the church have their knickers in a twist, you'll need to enclose the radiators (and traps and valves...).

ChrisJ

Generally speaking if a child touches something and it hurts they stop doing it.

More than I can say for a lot of adults but that's another subject.

JUGHNE

One hot touch of anything, is lodged in your memory and stands ready to protect you in the future. (soldering fittings, changing light bulbs, 50' of garden hose laying in the sun, etc.

But if there is a pre-school room or nursery where crawling or walking/fall down toddlers, who cannot react with the pull back reflex quickly enough to avoid serious burns, for that area I would consider covers/boxes.

Sailah

JUGHNE said:

One hot touch of anything, is lodged in your memory and stands ready to protect you in the future. (soldering fittings, changing light bulbs, 50' of garden hose laying in the sun, etc.
.

Then why do I keep burning myself soldering?

And I still eat pizza right out of the oven, you'd think I would learn...

You got burned by a garden hose?

I agree on the Sunday School area it might be a good idea to enclose the whole thing.

JUGHNE

Only once by the garden hose; leave 50 to 100' of black hose full of water laying in the sun. Go to get a drink or wash your hands and it is a quick lesson of the power of solar heating.
There was a news story of mother in Arizona who turned the sprinkler on for the child to run thru.....burned enough to go to ER and get on the evening news. It was over 100* there that day, but 90* amb will do it also.

"It takes a Village (of insurance companies)"..... to assume the liability for a child who suffers from parental neglect as the child is raised as a free spirit so as not to lower their self-esteem.
(Everyone gets a ribbon BTW.....)

PS: we keep burning ourselves just to reinforce that memory of protection......sometimes in my case it is just a senior moment.

RPK

I was mistaken when I used the term "radiator". The emitters are enclosed fin-tube convectors. So the only hot surface that are exposed are the thermostatic traps. My google search on insulating traps led me to multiple sources that do not recommend insulating thermostatic traps because they will cycle less frequently causing water to back up.

I agree, learning not to touch hot things is an important life lesson, legal questions aside. The church wants to know if covering/insulating the traps could cause any mechanical problems. They will do this themselves if I okay it.

This is the first source I found suggesting that insulating traps was not advisable:

Www.thermaxxjackets.com/what-types-of-steam-traps-can-you-insulate/

Other sources are easily found, including one post on heatinghelp from back in 2006 by a now deleted user.

ChrisJ

There's no better person to ask this than @Sailah and it looks like he said insulating them won't hurt anything.

I'd say full steam ahead.

JUGHNE

Thinking that some louvered/decorative/ornate cage or box would look better than exposed insulation that could get beat up by the vacuum cleaner. IMO

Sailah

Thermostatic traps work based on a temperature differential. So if you insulate the brass, it'll hold the heat longer in theory. This is a datalog from a steam trap monitoring project I am working on. I'm measuring in Celcius right on the trap. You can see how fast it fades once steam is turned off. Because the trap is connected to the radiator it will cool at close to the same rate.



Thermostatic traps also drip constantly while under load. It's not an "event" where there is a sudden gush of condensate flowing.

So in my humble opinion, insulating a thermostatic trap will have a negligible effect on it's performance, certainly won't hurt its durability and save a pittance in efficiency. You'd put it on simply to shield it from kiddos.

That said, a far far cheaper alternative is just to use an oven mitt. Buy one for a couple bucks, slit it open and sew on a velcro closure. That's what I would do. I bet the congregation has a dozen people who could sew one up in a jiffy.

I know the Thermaxx crew well and I think their parts are a little overkill for what you are trying to do.

Sailah

I read Thermaxx's treatise on insulation and I take issue with their thermostatic reservations. It's true thermostatic traps operate by subcooling the element enough that the plug comes off the seat to drain the condensate. But the difference is minor because the convector or radiator will pull the heat out just as easily as the ambient air.

The notion that condensate can't drain because you have a blankie on the trap body is nonsense. And the ensuing water hammer scare tactic I don't buy. Float and thermostatic traps use the same element to evacuate air and are just as susceptible to water hammer.

I think the real reason is that it makes zero economic sense to put a $100 cover on a $50 trap to save $0.28/yr

I'll put an insulated cover on a radiator trap I have and post up the datalog results

ChrisJ

@RPK
@Sailah works for Barnes and Jones, who is a huge manufacturer of steam traps.

Point being, you're getting this right from the horse's mouth, not just some dude on a forum.

KC_Jones

For this situation wouldn't a simple heat shield of some kind serve the intended purpose? A small air gap and a thin piece of sheet metal can work wonders for protecting against little hands and probably a lot cheaper.

RPK

Thank you all for your input. Great to be able to get such qualified advice the same day I posted the question! Thank you Sailah! They are considering covering the traps with inexpensive PVC insulation fittings (held together with those little push pins, so they'll be removeable). I do like the oven mitt idea!

Sailah

Here's my test mule. I have my thermocouple foil taped to the trap body and another downstream on the condensate line.

I wrapped the brass in a few layers of T shirt material, then 2 thick layers of that foam, each overlapping. I think it's as good an insulator as you can reasonably expect. And quite the looker if I do say so myself I know we can't discuss pricing on the wall but I can make these available lol

I'll post up the screen shot of the temp logs when the boiler kicks on tomorrow. Should be able to match it up with the same uninsulated trap and graph them together to see what the cooling rate is. I'm draining to atmosphere so I can verify condensate is discharging.

JUGHNE

The Quilting Group of church ladies could copy that and market it

gerry gill

Maybe if you put that rig up on the trap, once the people see it, and recover from the sight of it, they will no longer complain about the issue , after all..lol

Sailah

In the interest of my pretending to be a scientist I ran the following experiment

In comparing an insulated thermostatic steam trap to a non insulated steam trap I was interested in the following.

• How long does it take for the trap to cool insulated vs non insulated?
  
• What effect does the insulation have on the subcooling of the element?
  

I already had the data for a non insulated trap. Since the insulated trap had higher temps, I started both at 79C which is hottest the non-insulated thermocouple got.

Non Insulated took 37.40 minutes to have a Delta of 35 C (Delta 63 F)

Insulated took 42.00 minutes to have a Delta of 35 C




In addition to checking temperature of the traps I'm also able to "look" inside a trap and calculate the actual subcooling time of the element

This test was done on the non insulated trap. I'm measuring outside trap temps so we'll have to extrapolate a little.

When the steam is off the trap starts cooling. It takes about 2 1/2 minutes for the trap to cool from 78 to 71 C (or 172F to 160F) at which point the plug has retracted off the seat and there are zero restrictions to condensate draining. You can also clearly see the delta of 6C (or about 12 F) of subcooling required to move the element. This is due to the lower flash point of the liquid in the diaphragm.



And here's a global picture of a trap opening and closing. The cage unit reacts almost instantly to steam, far less than a second, but the temp you are seeing is the trap body so there is a lag on teh graph that isn't there in real life



anyways just some ramblings I thought would be interesting to the trap geeks