Antifreeze Protection for a Pumphouse

Definitely heat tape on the pipes and use insulation to keep the heat where you want it.

A dragline I worked on had heat tape around the grease lines so the grease kept pumpable during the cold winter nights. Control was by measuring the equipment house temperature as well as the exterior temperature and turning on the heating in areas needed.

Cost of heat tape is a one off and very economical to run.

Well the first thing I would consider is that the more insulation you have the less heat you will use....the insulation you pay for once, but the heat is forever...so on such a small enclosure I would suggest R-30+ and probably would go at least R-48...which is about 8-9" foam or 16" of fiberglass...I would probably go with 3" of foam board exterior and R-30 fiberglass interior....You could probably heat the interior with a hundred watts...but I would probably go with heat tape strategically placed around the pipe and tank...

Assuming 45º inside and 0º outside, that is a 45º temp difference.
The total surface area of the pumphouse is 264 ft².
Three inches of foam board gives R15 of insulation, plus a bit more from the siding and sheetrock.

(264 x 45)/15 = 792 Btu/h of heat required. 792/3.41 ≈ 232 watts.

SE's choice uses more insulation and less wattage; this choice uses insulation that will fit between the wall studs and rafters.

I would look for a 500W ceramic-block type of small space heater. That gives some reserve; and it will run only as needed to maintain temperature. The heater will be 120V single-phase, which you can get by using one phase and neutral of your 208V system.
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That is probably simplest. The heat trace option is also good. Because of the smaller area of the tank and the short run of exposed piping, 100W of heat tape should be plenty, along with tank and pipe insulation.

Two thermostats.

Not my idea, but the advice of an Alaskan coach driver who got home to a flooded basement when the heating did not come on. Two homes can afford back-up.

I recommend a heat tape as well.

They are frequently used in reptile cages,but there are many other uses as well, such as your applications.

They come in various widths and lengths,and are customizable.

There are wide widths suitable to wrap an entire tank,and narrow ones for piping.

Check this link for more info:

https://www.reptilebasics.com/heat-tape

There are more sources than the one I listed,so you might want to shop around for the best price.

These do not come with a thermostat,but MUST have one installed.

I also recommend a thermal cut off device (TCO) under the tape.

This is a back-up fail safe device that will open the circuit if temperature exceeds it's design limit.

Two connected in series at different points on the tape if you are a belt-and-suspenders guy.

An example is a CANTHERM SDF DF0728.

It is designed to open at 162F,and cost around $1 each.

Be safe, not sorry.

You could also go so far as a freeze temperature alarm with a battery backup....

https://www.absoluteautomation.com/temperature-alarms/

Why in the world do you have a pump and water lines above your frost line? How can you have this plumbing and meet local building codes? The frost line of Seattle, Washington is just 12 inches. Dig a two foot deep hole inside this pump house to recess your pump and water lines and then put a proper insulated cover over the hole inside the house.

Redfred,

The pumphouse was built in 1946 and likely met codes of the time. The pumphouse is on slab. The pump is submersible as referenced in my original post. This picture shows the situation.

Thank you everyone who has replied with different solutions, much appreciated.

So this should not be a new problem. Do you know how the pipes in this pumphouse didn't freeze and split during any of these days?

There have been portable space heaters doing the job in the past, one electric fan type and one propane type. One of the old wall outlets had some kind of meltdown and was visibly burned out. There was a fire on the opposite end of the structure I suspect came from a homemade smoker. I have refurbished most of the structure over the last few weeks. This pump room is the last part of the project.

So this is now a classic example of what I call a "financial engineering" decision.

IMHO the "correct" way to mitigate this is to put everything, including that storage tank, below the frost line so even a long term power loss in winter will not freeze any water contained in a pipe, tank or pump housing. However, this solution is expensive and significantly time consuming to implement.

The use of heater tapes wrapped around the pipes offers a frugal solution that will likely prevent most scenarios of freezing/bursting pipes. What I dislike of this approach is two fold:

First, these rarely needed heaters are not monitored for failure. Adding heater tapes and not monitoring can induce a false sense of security. Adding complicating alarm circuitry requires somebody knowing what to do and responding when the alarm sounds.

Second, mixing electricity and water presents a possible shock hazard. Care in the placement of disconnects and GFCI devices must be considered.

A heat tape is the cheapest and easiest way to solve your problem.

They are available in different lengths with a built in thermostat that turns on at 35F and off at 45F.This is the cheapest and easiest way.

Most hardware stores carry them.

Just remember do not overlap the tape.

Self-limiting heat cable (vs heat tape) is the better product for your application. You still need thermometer controls, but it won't overheat and the temperature range is a better fit for keeping a pipe above freezing.

https://oemheaters.com/topic/heating-tape

I've heated larger and colder spaces with a 100w bulb.

..if I were worried about power outages. I'd heat the pipes as well as a local barrel of water with a small immersion heater. ..or simply the ambient heat.

The barrel of water will radiate heat for a long time in these conditions.

If I didn't want to spend a nickle I'd fill the area with 2 liter bottles of water and many blankets of insulation.

I've regulated temp in this way as well.

..more food for thought.

Wow, I'm amazed that the water would be so warm. My well water is so cold, I've given serious thought to using it to rig up an insulated cooler.

Map of ground water temperatures:

Self-limiting heat tracing tape attached to small-bore pipework, fed from a thermostat, and plenty of pipe insulation over it and the pipe is also an attractive solution and may well use less power than the <...1000W...> currently envisioned.

Domestic water tanks in the UK, used to pressurise the hot water part of the plumbing, are usually mounted in the loft space and arranged so that, as far as thermal insulation around and over them is concerned, they are part of the house. That way there is no need to trace-heat the tank as it picks up gentle warmth from the house below.

Water supply and waste water processing utilities often don't insulate exterior pipework above 8in/200mm diameter, as there is sufficient flow for there to be no need.

I grew up in Northern West Virginia. We insulated the space that the pump was in and used a 65 Watt incandescent light bulb. With many nights in a row well below freezing we never had the pump freeze.

I specify incandescent because I recently saw cheesy bread being "kept warm" with a CFL.

In my well pump pit I use a small (750/1500 watt) milkhouse style heater set on 750 and the thermostat set low. Cheap and reliable. I have had problems with heat tape and incandescent bulbs burning out in the distant past.

I wouldn't have thought of the idea of geothermal heating from circulating wellwater. Perhaps not the quickest/cheapest solution, but maybe the most elegant.

Never having subzero temps is rather enviable.

Here is a caution for you, it appears from the photo you posted that the piping is metallic, if I am wrong and if you elect to use heat trace...

If you have PVC or ABS pipes, make sure you do not wrap the heat trace around the pipes. Attach the trace only to the bottom of the pipe. Why? ABS and PVC pipe do not flow heat like metal pipes do and heat trace on the top portions and sides can cause hot spots because of the difference in thermal conductivity. Many fires have resulted from people wrapping heat trace around such pipes.

North of 60,

You are right that the "typical" heat trace cable can do the things you describe. Most manufacturers of it caution against using it on any plastic piping. However, the self-regulating heat trace cable I have described is safe to use on PVC, ABS, etc. piping because it automatically adjusts the heat output everywhere along its length. Try it some time.

--JMM

Agreed... and I have used the self limiting type. However, as our section of the government where I worked included the Fire Marshal's Office, I have seen the fire reports that back up my warning. These fires have and do happen, hence my note of caution.

While underground piping, etc. would be a more permanent solution, your solution is common and works well.

As long as you insulate properly, your 1000 watt heater will work nicely.

Downsizing your heater might be cheaper, but the smaller heater will run longer (the total electricity use will probably be close to the same).

I place equipment that must remain above 32F to properly function in portable enclosures all over the world, including northern Canada.

How do I do it.....twin 5000 watt heaters (one is a back-up).

The only difference is my systems are site critical and therefore I monitor the temperature.

You're just looking at frozen pipes