A hundred random plumbing-related questions.

[WaterTight]

Well, 7..

1. a) Why do some plumbers install some radiators on the hot water circuit? To not have to drain down?

1. b) How much more expensive (if at all) are the special rads you'd need to buy if fitting on hot water circuit?

1. c) Is there any way to externally recognise a rad on the hot water circuit for purposes of isolation before work?

2. If one or more rads on a system needs to be bled relatively often, what would the likely cause(s) and troubleshooting methods be?

3. If you switch the heating and hot water on simultaneously is there always hot water priority? Is it different depending on whether it's a combi or system boiler?

4. Can you over-ride what the priority is set at? i.e. feed both equally or one over other...

5. Do you need special flush valves for low-level cisterns or do you use the same as on a close-coupled?

6. If you were drilling through a wall and drilled through a live cable (presuming you're holding a insulated drill and so won't die) and it shorts out the electric... what do you have to do to make that run of cable in the wall and the spur it feeds safe?

7. Some boilers I understand (possibly just combis?) have no pilot light and all-electric ignition. What's the benefit of this type and how standard are they?

 

[justlead1]

Hi
Q. 1a On the primary circuit or hot distribution pipe?
1b If fitted to an hot distribution pipe or direct system F&R the rads/towel rail need to be of copper or brass more expensive.
1c Ask client of system history/performance. Possible greater temp difference on flow and return at rad whe gravity feed. Turn off any circulating pump off, monitor heating does it cool at same rate. If secondary return on hot water system, isolate and monitor rad temp. Via air valve purge water into a vessel, if squeaky clean probably open circuit. Scratch rad with a knife to identify material. Trace pipes.
2. Systems pulling air from some where. If you ever find an instant solution bottle it you will be a million air over night.
3. Dependent on the control wiring/settings, although i seam to think is the norm on combi's.
4. Yes but why?
5. Try not to get involved with them of late but think there the same. There will be poeple that know for sure.
6. Cut a box in the wall, connector in box and blanking plate. (plumbers method)take advise from sparks.
7. Use less gas, Probable cheaper to manufacture and fit. So they will become more popular across the board.

 

[migoplumber]

you answer the questions first, then we will have a pop.

 

[REDSAW]

weird q#s
yes on 2 no on 4
& ??? why?

 

[Renewable M]

If you have this many issues my friend, I advise a qualified plumber/heating engineer.

You'll never get your head around that lot in a zillion years, no offence meant but theres a broad spectrum there!

Doing up a house on the cheap rarely tends to be cheap.

 

[WaterTight]

Cheers for your answers justlead.
I've no actual need to know any of these answers, just questions that come to mind. I work as a plumber's mate for a bloke but he's not exactly mr chatty so questions are difficult to get answered.

you answer the questions first, then we will have a pop.

On this board you'll be made to feel stupid enough for asking questions alone, attempting to answer them as well would be suicidally stupid.

weird q#s
yes on 2 no on 4
& ??? why?

Weird q's? Didn't think they were so crazy, but oh well. And number 2 wasn't really a yes or no question...
And why? Why what? Why ask questions? Good question. I often wonder that myself. But unfortunately I have plenty more to infuriate you all with so watch this space.

If you have this many issues my friend, I advise a qualified plumber/heating engineer.

You'll never get your head around that lot in a zillion years, no offence meant but theres a broad spectrum there!

Doing up a house on the cheap rarely tends to be cheap.

These are just hypertheticals so no house will fall to pieces. And it may take me a zillion years to get my head round some of these things but since my intention is to manage to do so it can't hurt to give it a try.

I'll try and guess an answer to one of my questions then...
The one I didn't really get an answer to

Well, 7..

2. If one or more rads on a system needs to be bled relatively often, what would the likely cause(s) and troubleshooting methods be?

This is the case in my friend's flat. But when I asked the plumber I work for all I got was "Hmm, there's a problem there."

So I'm guessig some of the things you might do is maybe first try bleeding the rest of the rads to make sure there's no air in the other rads. Then bleed any vents on heating circuit in airing cupboard or elsewhere. Doing it when system is cold. If prob still happening then check water level in f+e tank to make sure air isn't getting in there. If prob still there maybe air locked somewhere? So introducing mains pressure to flush through at one point while draining it from another..?

Any of that make sense? Or ridiculous through and through?

 

[so-solar]

makes sense mate! but try and think about pump positioning and pump speeds, vent pipe positioning and correctly installed. Make sure you are bleeding with the pump off. It could be alot of things to be honest but it is an ongoing problem that heating engineers will come across for many more moons!

My input to your question, if you hit a cable call a sparky buddy!

Dont be afraid to ask questions and if you do answer it wrong on here it is far cheaper than making the mistake in somebodys house. To be honest there is not a plumber in this world that can answer every question asked.

 

[migoplumber]

i'd of had a go at questions, but just thought it was another lad, with a test tommorow at college, that couldnt be bothered to find the answers.

if your really working for a bloke that wont answer these fairly simple qustions for you, then i think its safe to imagine he dosnt want you to progress too much!

if you ask a question, then reply with your answer, i think you'd be taken more seriously, yes people might take the mick, but at least your being genuine.

 

[so-solar]

as above!!!!!!! well said...............

 

[Bernie2]

I think the problem is that perhaps it may have been better to put one question at a time up. Getting a load all at once can be a bit daunting.

Anyway here is a possible part answer to number 1

I'll mail more as I think about them.

1 (a) Seems fair to say, that the thinking behind it may be one of practical application. The rad on the hot water circuit is usually there, either as a solid fuel heat dump or to warm the bathroom.

Its assumed that if you are heating water you might want a bath, so heating the bathroom rad only makes sense. On a modern system it means in the Summer you can warm the bathroom without having to put all the heating on.

In the old days many houses had no central heating, but they could have a heated towel rail in the bathroom, heated off the Primary circuit which acted both as a rad and a towel airer.

In the days of solid fuel, often there wasn’t any heating circuit, so solid fuel back boilers and direct cylinders could get so hot, the water bubbled in the cylinder.
It was always a bit dodgy to get the temperature under control then, as often the fire grate brickwork absorbed heat which stayed outputting to the back boiler long after the damper was shut and so the rad helped take up the spare heat.

That’s beside what Just lead has said, which also helps explain it.

1(b). No off hand idea as to price, but has to be good quality that will not corrode easily usually copper, that is of course, if its used on a direct cylinder primary circuit.

1 (c). Visually may look like a towel airer or not. They usually look like some form of square frame to hang towels on. But you can get them that look like ordinary rads.

You can usually heat hot water and shut C/H off, if it gets warm, its on the hot water circuit.

To go into all the details would take ages I am afraid, but feel free to ask whatever you want. Nobody will treat you as daft, there are probably things you know many others might not know. And information should be free to all.

 

[Puddle]

i'd of had a go at questions, but just thought it was another lad, with a test tommorow at college, that couldnt be bothered to find the answers.

.

I did'nt answer the questions because i thought there was another 93 to follow

 

[Bernie2]

Question 2 Part 1.

Air in system

2. Could be many reasons depending on system. Take the easiest first.

A sealed system such as a combi circuit obviously doesn't have many places to pull air in, hence the name sealed system.

However it does have other means of entraining air.

First of all, the water itself has air entrained, when the water is heated the air is released and should come out the auto air vent by rights but can also come out of the rads.

The more you top it up the more air you get out. But if your topping up all the time, then like a car tyre you must have a leak somewhere.

It can also be a part result of corrosion.

The system can also pull air in, through loose glands on valves or through the walls of plastic pipe. Air molecules are smaller than water molecules, so they will go through the walls of plastic pipe but water can't come out. Its why they use barrier pipe on central heating systems, its covered in a substance that blocks the air holes.

Also high system water temperatures can make soldered joints slightly porous. The solder shrinks and can make micro sized holes that never leaked before leak.

Probably more reasons as well.

 

[Renewable M]

sorry watertight, didnt realise you were in the trade. It seemed a lot of questions, thought there was a diy project in there somewhere.

Always happy to be wrong!

Question 2: older systems that are corroding inside after a change of water after maintenance and not enough (or no) inhibitor poured in can produce a billion tiny gas bubbles that will find somewhere to settle. It's one other answer, not definative.

Question 3: common 3 port valves have priority hot water. when power is off they spring to open port b. see here

Hope this is helpful. The honeywell data sheet tells you a lot.

 

[WaterTight]

makes sense mate! but try and think about pump positioning and pump speeds, vent pipe positioning and correctly installed. Make sure you are bleeding with the pump off.

Thanks so-solar. Yep, I follow all that. Bleeding with pump off though.. Is that because even if the heating is off the pump might come on if you bleed because it triggers a flow switch or something?

if your really working for a bloke that wont answer these fairly simple qustions for you, then i think its safe to imagine he dosnt want you to progress too much!

Unfortunately so but I'm a beggar who cannot afford to be a choser so I have to make the best of what I've got. He's a good bloke but likes to concentrate fully and get the job done in good time. Answering questions is way down the list of priorities.




Some fascinating insights there Bernie. Loved the plastic pipe letting air in bit, had no idea. And the logical explanation behind bathroom rads on the hot water circuit. Thank you very much for your answers. I look forward to more when you have time. You don't need anyone to work for you do you?

It seems like there are a billion possible reason why air may get into a system. At the moment I don't understand how anyone could go about finding out which one(s) are causeing it... apart from tearing the house apart.

Question 2: older systems that are corroding inside after a change of water after maintenance and not enough (or no) inhibitor poured in can produce a billion tiny gas bubbles that will find somewhere to settle. It's one other answer, not definative.

Thanks Renewable. So a good first step would be to ask the customer when maintenance or work was last done then. I guess it's always good to find out as much as you can from them first.

 

[Bernie2]

Part 2 of 2

Once again air can get in to a system from those places mentioned i.e. glands, corrosion, filling and refilling system, plastic pipe.

But a vented system also has a feed and expansion tank and air can get in through either the vent or the cold feed.

The vented system, like the sealed system usually has a pump, that if installed in the wrong places entrains air into the water quite easily.

Even expansion water mixes with the aerated water in the expansion tank.

Then you can get blockages and air locks which can also cause air ingress. In short there are many ways air can get into a vented system. But usually if the vent and cold feed are in the right place its not so much of a problem.

For info about the pump positions I would try J Macs Pump tool website and Danfos for the 3 tee rule.

As to trouble shooting. Well there are so many different ways you can install central heating its hard to say. However if you learn the basics you can work some of them out your self.

I always work on the idea, after I have checked the reasons I have mentioned, that "A pump sucks one end and blows the other". Where is it in relation to the vent and what is it doing?

You can as some one has said, place a glass of water over the vent end in the expansion tank and see if it draws water in. That at least helps you decide if it is the vent drawing the air in. After that look at how the system is supposed to work and what is wrong with it that may make it not work.

3. Hot water priority.

Well yes and no. If its a system with 2 - 2 port valves such as a Honeywell Sundial "S" plan you can choose which valve you have open.

If its a Honeywell "W" its got a 3 port diverter valve which as you say usually gives priority to the hot water. You can alter it though.

If its a Honeywell "Y" plan it does the same but uses a 3 port mid position valve to allow both at once.

Basically though, you can choose which you want to heat. But if you call for both at the same time a mid position valve and 2 port valves, give you both, the diverter valve one or the other usually the hot water.

Once again I would advise registering free on the Honeywell heating site and taking a look, even if the valves on a system are not Honeywell they usually work the same way.

The valves are perhaps best thought of as electric stop taps. I find it easier that way, when you start linking in other controls i.e a valve will not open if its temperature controller tells it not too.
A temperature controller will not work unless its programmer or boiler tells it not too. A boiler can have an auto frost stat or weather compensator that works the boiler independent of the programmer. Have a look at the controls you can get for heating systems, its amazing what you can do. But try to think simple, even though the descriptions are sometimes complicated. Switching a boiler on using a remote control is only switching a boiler on.

A combi usually always give hot water priority over heating. The thinking is that you will not run hot water for very long ans so the heating will not cool down to much for you to notice its gone off.

Question 4

Yes you can usually wire it to change priorities.

5. Not sure what you mean. Sometimes the syphon is different, sometimes the same. The ball cock come sin about 3 varieties High, Medium and Low pressure. Usually its just the seating that is changed.

6. In reality replace it or splice it with a sealed junction box perhaps, but usually replace it. It depends on a lot of things. Best ask the "Sparks" forum.

7. They are becoming more standard, it saves fuel and also stops the pilot light from impinging on the heat exchanger causing localised corrosion and wear.

But to all these questions more could be added by many others.
Good fortune!!!

 

[WaterTight]

Thank you very much Bernie, very informative as always.