How to install a steam boiler

It is common to find many types of steam system components installed incorrectly. In this example, a mechanical check valve that requires gravity to operate properly is installed upside down.

It is impossible for this check valve to function when installed this way. However, it is probably a good thing that it is upside down, as it is also installed backwards. If it were installed upright, it would block flow in the wrong direction. Failed Valves. This valve is obviously stuck partly open. However, often valves are installed with pipe on the down-stream side.

High and Low Pressure Systems Interconnected. In facilities with high and low steam operating pressure systems, all steam and condensate lines should be properly identified and checked.

Be sure that high and low pressure systems are not interconnected at any location, even on condensate systems. High pressure condensate can flash to steam in low pressure condensate systems causing problems with their operation and wasting steam.

Use a flash steam recovery system to flash high pressure condensate to steam and then inject the steam into the low pressure steam system. Supply Lines and Condensate. Long steam supply lines should be trapped to remove condensate and keep the steam dry. In the photo to the right, there is a steam trap off the steam main, and condensate is returned to the to the top of the condensate pipe. Because condensate is on the bottom of the pipe, this trap is doing nothing to help keep the line dry.

Worse, not only is it not removing condensate, it is actually wasting energy. Steam comes off the top of the Steam Main, comes down to the trap along the vertical pipe in the left of the photo, as it is cooled by heat loss from the pipe. Note the nice insulation job however; this is probably keeping the problem from being much worse. Condensate should always be drained from the BOTTOM of the steam line in low sections of pipe and at changes in direction, such as a 90 Degree turn.

Condensate from steam traps should always be returned to the TOP of condensate lines; the maximum height of rise above the steam trap to the condensate line is a function of steam pressure and the type of trap. A general rule of thumb is that 1 psi of steam will raise water about 2 feet. For example, a 5 psi system should not have condensate lines higher than 10 feet above the steam trap. Not only must steam traps be piped off the bottom of the steam lines, the pipe must be properly sized.

If the condensate drip legs are too small, the condensate will simply blow past the drain line. Your Gas Safe engineer will want to check a few things with you first. Such as how many radiators you have, your water pressure, the number of bathrooms in your home and the positioning of the current boiler and flue.

Make sure you get a fixed price quote upfront to avoid any nasty surprises. To comply with Building Regulations and Gas Safe rules, all Gas Safe businesses need to notify the local authorities whenever they install a new gas appliance. And they should give you a Building Regulations Certificate , as well as a completed Benchmark Certificate, to prove compliance.

Most reputable companies will offer you a guarantee on their services. Here at British Gas, we offer a five-year warranty on our installations, but these terms may vary from business to business. So always check before agreeing to the work. Hopefully you feel a bit more clued up on your boiler installation now, but if you still have any questions, our heating advisers are on hand to help.

And, for more information around British Gas boiler services, visit us here. Book a free appointment. Step-by-step guide to boiler installation.

What types of boiler are there? Q: Does it matter which side of the Hartford Loop I tap into? A: No, either side is fine, just keep that return tapping below the boiler's water line. Q: Can I supply and return from the same side of the boiler? A: You shouldn't enter and leave though the same section because the zone water might not have enough time in the boiler to pick up the necessary heat.

Ideally, you should pipe from opposite sides in a diagonal pattern. Like this. Q: Can I pipe straight through the boiler's mud leg?

A: No, because the water will zip through the boiler too quickly. It won't pick up enough heat, and you'll have a call-back for sure. Q: Suppose there's no way I can tap directly into the boiler.

Does that mean I can't zone with condensate? A: You can still do it, but you have to use a bit of creativity. Here, just follow this diagram. Now, screw another C X M adapter to the other side of the bushing. That's your return tapping. The copper tubing reaches deep into the boiler's mud leg and deposits the cooler return water on the side opposite the one from which you'll be drawing your hot supply water.

You'll take the hot supply from the bull of the tee. By doing it this way, you'll get the circulation you need across the boiler to pick up the heat for the zone.

Q: Do I still need a bypass line if I pipe it this way? A: Yes, the bypass allows you to temper the water as it leaves the boiler. The bypass keeps the water from flashing steam when the circulator shuts off. Q: How do I start this one up? A: Fill the zone with water by using the two boiler drains. Put a hose on 1 and purge back through 2. Let the boiler steam, and then start the circulator.

Use your two ball valves to blend the water through the bypass until your supply temperature reaches degrees F. Take the handles off the ball valves and you're all set. Q: Before, you said I shouldn't pipe directly through the boiler's mud leg because I wouldn't pick up enough heat on each pass. Does that happen with this system?

A: No, it doesn't because the copper tubing injects the water deeply into the boiler and forces it to reverse direction before it can leave the boiler. This action makes the return water at the bottom of the boiler very turbulent. It mixes things up, allowing you to pick up the heat you need for that zone. Q: With any of these systems, should I put a strainer on the inlet side of the circulator so I don't suck mud out of the boiler and into the circulator?

A: No, because the strainer can produce a very large pressure drop at the circulator's inlet, especially when it gets dirty. That drop in pressure can make the circulator cavitate. Q: Well, what's to keep the circulator from clogging up then? A: If you choose the right circulator for this application you won't have a problem. I like to use a 1, rpm three-piece circulator for these zones because they have larger and wider impellers than their smaller, high-speed, wet-rotor cousins.

A larger circulator fares better on this application because it can pass more debris through its impeller. Q: Should I use an iron-body circulator? A: You could, but a bronze circulator will last much longer here. Condensate usually has a good deal of carbonic acid mixed in with it. Bronze is a much better material than iron for this service. Q: How should I control the zone? A: The simplest way is to use a room thermostat to operate the circulator through a double-pole, single-throw relay such as Honeywell's RA.

You'll also need a single-pole, single-throw, immersion-type aquastat such as Honeywell's LA to set the maximum boiler temperature when you're not making steam. Wire the controls so the circulator and the burner come on at the same time. The burner will bring the boiler water up to degrees F and no higher. The aquastat sees to that. It will shut the burner off, but the relay will keep the circulator running as long as the room thermostat continues to call.

By setting it up this way, you're able to supply hot water to the zone without making steam. As far as the folks upstairs are concerned, the steam system and the hot water zone are totally independent.

Q: What if the steam system just shut off and suddenly the hot-water zone comes on. What happens then? A: The boiler water temperature will be higher than the degree F of the aquastat so the zone thermostat working through the relay will start the circulator, but not fire the burner.

Simple, isn't it? Q: Could I pipe an indirect domestic water heater off a steam boiler using the same piping techniques I would with a heating zone? A: Yes. Just treat the indirect heater as you would a radiator. Make sure you blend return water into the hot boiler water to limit the supply to the heater to degrees F Here's a sketch.

Q: How many hot water zones or indirect heaters can I take off a steam boiler? A: That depends on the boiler's capacity. You can't take out more BTUs than you put in. I've seen people try to add one too many hot water zones and when it came time to make steam, they were out of luck. Q: What's a practical limit for a house? A: Again, a lot depends on the size of the boiler. That'll deliver 40, BTUH, or so to the zone. That's enough to heat a good size zone. A: Because you're playing with the boiler's pick-up factor.

The pick-up load usually represents about a third of the net load, depending, of course, on how the installer sized the steam boiler. Q: What is the purpose of the pick-up load? A: The pick-up load gives you the "extra" capacity the boiler needs to heat the pipes as the steam heads out toward the radiators. Q: Is the pick-up load always available to me?

A: No, it becomes available to your hot water zone only after the steam pipes have heated up. Q: How about if I'm not making steam? A: If you're not making steam, the pick-up load and the rest of the boiler load is obviously available to your hot water zone. Q: So the pick-up load sets the limit on what I can do with this zone?

Q: Let's say I'm sizing a new steam boiler and I want to use one or two hot water zones. Never add the hot-water-zone load to the steam load when you're sizing a replacement steam boiler. This is a game of subtraction, not addition. Size the steam boiler first. Base it on the connected steam radiation load, plus a suitable pick-up factor, not the heat loss of the building.

Then work with the available pick-up load to size your hot water zone or zones. You can't take out more than what's there. Q: What happens if I over-size my steam boiler? A: You'll have problem with the steam side of the system: surging water lines, water hammer, uneven heat, high fuel bills. Q: Could I wire the boiler for priority. You know, either make steam or run the hot water zones, but not both at the same time? A: Yes, but this limits the usefulness of the hot water zones.

Suppose you want some heat but you can't get it because the steam zone is calling? Or vice versa. Toggle navigation Answers in minutes.

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