Squeezing copper tube?

I have discovered that the **** who installed the central heating in the house we recently moved into, did not bother putting a restrictor valve to adjust the flow through the hot water tank coil. This results in the unrestricted coil 'stealing' all the circulating hot water from the boiler, which results in

1) the boiler getting hot too quickly, and short cycling, and

2) the radiators in the house being starved of heat.

We can turn off the hot water on the programmer, which shuts the electric valve to the coil, and of course the proper solution will be to drain down the system and fit a restrictor valve in the hot water tank coil feed.

But I don't want to disturb the system during the winter, in case that unearths more horrors which put it out of action. So for now I am wondering about squeezing the 22m copper pipe to an approximation of the correct restriction. Any thoughts as to methodology and metallurgy?

PS, I am very well versed and experienced in plumbing and central heating systems, and have experimented with balancing the radiators and adjusting the boiler etc, I just want your thoughts about squeezing a 22mm copper tube.

Thanks !

Not sure you could swage it down much before the risk of it cracking, there is always that a crack is hidden inside the pipe and let’s go when you are not there.. I would sooner drain it down and install a control valve.

If there is an electrically operated valve that interrupts the flow to the heating coil, then just fit a tank thermostat to control the valve.

Ian P

Squeezing it down to what size? How do you intend to squeeze it ?

Fresh pipe is pretty malleable and I have hammered it flat without splitting but it may age harden a bit. I would be inclined to give it a go but have plan B ready to go if it does split.

Mike

I think squeezing the pipe is a rubbish idea!

If the person installing the heating originally was an **** then it seems likely they were also an **** electrician.

I'm not sure what electrically operated valves are available currently but I think even the (oldish) Honeywell 'Y' Plan actuator could be set up to 'stop' at part travel. Whilst basically a crude/simple design it is never the less quite ingenious. It has a small synchronous motor that moves the valve to the open position against a spring, cutting the motor power then allows the spring to return the valve shut. There is a microswitch inside the valve that detects the 'shut' position and puts a diode in series with the mains power (which is now trying to drive a stalled motor). so that the motor only 'sees' half wave AC which locks the motor rotor whilst at the same time reducing power consumption. As far as I remember (its 40+ years since I messed with one) there was some way of using the diode to stop the valve at some intermediate position.

If you have an existing CHG system that already has a electric valve then there should already be a tank thermostat, maybe its just not been wired up correctly (or at all).

Ian

by moving a the fa

Odd, I have lived in 2 houses with a similar system and they never needed a flow restrictor to work properly, even with 10mm piping on the CH side.

Being well versed in Ch systems you have already manually set the Y valve lever to the manual position, which gives you both CH and HW at the same time (till the valve gets energised again by the controller) and found the CH still runs poorly.

This being the case loosen a rad bleed valve downstairs, if the water is as black as engine oil you may have a system full of rust and that's why the CH flow is poor. Rust has a nasty habit of blocking the lowest pipe run.

BTW as you're new to the house, when you drain the CH down do check the system has refilled, the ball valve may have stopped working and dry boilers aren't funny.

Don't forget crimping the pipe will try to shorten it which might give you a leak.

Just a couple of thoughts. I have never seen a system with a "restrictor" you want maximum flow to the hot water loop until hot water temp is satisfied and then the Y valve will shut off flow and concentrate on the heating circuit if demand still there. I built mine as S plan with mechanical bypass for overun. 2 port valves.

However I had a fault with a relations Y plan after a plumber had wired the Y valve the wrong way round (after replacing hot water cylinder) so was driven by opposite demands of controls. Had me foxed for a while. There is nothing to say that yours hasn't been wrong for a long time.

You could look at it as having a reservoir of heat waiting there to get your CH off to a running start.

Otherwise, why not simply program your hot water to start heating a short while before your CH - then the HW circulation valve will be shut by the time the CH comes on and your problem will be no more.

Interesting, thank you for the replies.

This system I have inherited has two on/off water valves, one for the CH, one for the HW, instead of a single 3 way diverter valve. Both valves seem to be wired and operate correctly, (and I recently changed the electrical head of the radiator one, as it was U/S). Each valve responds to its respective thermostat and moves to it's open position, at which point it presses its microswitch to enable the boiler.

When both heating and hot water are both demanding heat, both valves are open, but the 22mm water loop, with no restrictor is stealing all the heat, causing cold radiators, and boiler 'short cycling'.

In the systems I installed myself, I put a restrictor valve on the hot water cylinder loop to balance it with the all radiators to prevent this 'heat stealing'.

As I stated in my original question, I don't want to drain the whole system down at the moment, (and have to buy expensive inhibiter), to install a restricter valve, because that will be too much disruption and might reveal other problems which might prevent the system working if I disturb it. I don't want to be without heat just at the moment. Nor do I want to get into a big production; fixing and possibly reconfiguring the system right now. When It gets warmer, I will of course drain the system, add the valve, clean it all out and vibrate all the radiators to loosen any crud; and install a magnetic cyclone filter and do a proper job. This is just a temporary fix.

I cannot program the CH and the HW to come on separately, otherwise obviously, I would have done ! In the near future I will be installing a Drayton Digistat RF902 controller, or maybe a more comprehensive heating controller, with electrically controlled radiator valves, allowing me to switch individual radiators off and on remotely, according to a programmed schedule, without having to go round adjusting them manually.

So my question was more along the lines of what might happen if I squeeze a length of copper pipe to semi-flat, as a temporary and crude fix? Might it crack?

And I was also asking if anyone could suggest a way to squeeze the tube, without removing it from the system. I am thinking of a G cramp with suitable protection against the pipe.

If you guys think the pipe would crack, I won't attempt it, although copper pipe can of course be cold bended in a pipe bender, so it might be OK (I can accommodate a bit of pipe shortening).

This is a temporary fix for a few weeks only.

Edited By John Doe 2 on 31/01/2023 19:29:00

Years ago, when in UK, I DIY-installed a couple of wet CH systems, in copper pipe. Some pipes were harder than others, and tended to crack when bent (with a proper bender). Annealing it made it softer than 'usual' pipe. So the pipe, as bought, has not been annealed. I would be very worried that your pipe will split.

Not sure how your controller is arranged. If you have two circuits, each valve-controlled, what happens if both are 'off' at the same time? I installed a pressure-sensitive bypass valve, necessary, I thought, because I fitted TRVs to the two CH circuits and the three circuits were electric-valve-controlled. Never thought about a HW coil circuit restrictor. Perhaps I was lucky.

(Redundant knowledge now. The climate in this part of NZ doesn't really warrant full central heating, even though domestic insulation standards are woeful. Anyway, DIY plumbing isn't allowed, and the components would be ridiculously expensive - you think UK is expensive?)

You have a water pump driving water through the radiators? what speed is it set at ? Some of them have 3 speed settings.

Murphy's Law says that a piece of copper tube in the workshop will not split when squeezed, but a piece of copper tube plumbed to a CH system in mid-winter will always split when squeezed.

Those of us who regard Murphy as an incurable optimist will also point out the corollary: It will not always split right away but will wait until you are out of the house and then split, emptying contents of CH system onto floor of house to await your return home.

Proceed at your own peril.

Edited By Hopper on 31/01/2023 23:24:33

I joined the Air Force in the early 60’s and was posted to a transportation unit, we moved large aircraft loads by road; this meant that we spent a lot of time staying in lorry driver digs when we were out on the road. I remember one such accommodation that was near Colchester, it was winter and we had temperatures of about minus ten at night, this accommodation had plenty of rads distributed around the room but the owner had obviously tried to prevent the cost of running the heating being excessive and he had crimped the pipes with what was probably a G cramp, the result was that first rad on the circuit was barely lukewarm and the others stone cold because the flow was severely restricted. It was one of the coldest nights that I spent out on the road, that night all of us on the team slept fully clothed in our uniforms and wet weather gear, it was freezing. Yes crimping up the copper pipe will severely restrict the flow but as others have commented will it or won’t it crack in the process, you may be lucky but it will be a gamble. Dave W

Would it not be better to just fix the "fault" correctly, the heating would only be out of action for a few hours?

The risk of serious damage just does not look to be worth the return, to me.

Jim

And what do you do when you realise that last squeeze was a bit too much?

I had a similar problem with our system. It seems that our system is an old system was originally a parkway coal fired system which had been upgraded to a gas fired Baxy Bermuda back boiler which we inherited. I had a Baxy condensing boiler installed to replace the Baxy and before it was installed a very strong system cleaner was run first for a few weeks. The boiler was installed in the loft next to the original pump and hot water cylinder. It ran ok for a while but i had the same ptoblems as you describe but the instaler couldn't fathom it and called the Baxy engineer who said it was s partial pipe blockage between the boiler and pump. The installer removed that section of pipework and he couldn't believe what he found. The old pipework it seems had at least 2mm a side coating inside which where he had cut into the old pipe it had dislodged and where the pipework had an elbow to the pump was blocked. The whole section was replaced and since we have had no problems.

David

Just wondering if this gadget would help you to get a restriction in the flow that you are wanting. Easy to fit no need to drain the system. Link

https://www.unventedcomponentseurope.com/aladdin-easyfit-isolator-starter-pack.html/

1970's copper was very poor, even phone cables went over to ali

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We have a similar system where the hot water is timed on for just 10 minutes each day and the heating timed as off. That 10 minutes keeps the tank hot enough for the two of us for washing up and hand washing etc during the day.

The old type of system without electric valves means that when you turn on the heating it will pump stone cold radiator water through the coil and cool down any hot water in there.