Plastic Piping on Hot Water System

paulrae

paulrae

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Plumbing ignoramus, so forgive the questions.

My hot water system is done completely in grey plastic piping. The fittings are stamped HBP15, and a bit of research suggests that these are hepworth fittings. We have an ongoing problem that the calorifier pressure relief valve regularly deposits sgnificant quantities of hot water into the bilges, so I want to fit an accumulator just after the calorifier.

The circuit will be calorifier output (currently an HBP15 90 degree elbow) to the accumulator (Jabsco, with a plastic tee-piece, probably not suitable for a proprietary fitting) then onto an HBP15 fitting a couple of metres away. I reckon that I might have to source an alternative accumulator with suitable fittings instead of the Jabsco unit.

My research also shows that these Hepworth fittings can't be removed without a hacksaw or the like, so I'm not keen on using them again. Any suggestion on what might be suitable to use? I've heard good reports of Speedfit - can I use this with the grey plastic pipe, or does it have to be used with a specific plastic pipe?

Any help/suggestions gratefully appreciated - other than rip out the whole system!
 
Hi There i am a plumber by trade and an accumalator should solve your prv problem but the accumalotor on the pressure pump should also do the same thing there isnt a lot of hot water so the expansion should not be a lot ? dont want to be overkill but an accumalator is a dead end and will be a harbour for legionella unless you can raise the temp over 60 deg c once a week . as for the fittings they are supposedly not interchangeable but you could join hepworth to speedfit pipe with a compression fitting making sure the inserts are in and then use speedfit if that makes sense
 
It sounds to me more like a problem with the PRV than anything else. If you already have an accumulator in the system, then that will already be doing the job you're talking about. You might want to try dismantling and cleaning the PRV before you go doing anything like fitting an accumulator, as that may solve your problem.
 
Just try and avoid copper!-at least plastic can expand a bit if required.I have just had to repair my piping in several places where it had frozen-no obvious way of draining system in winter.It did of course explain why I was getting my bilge full of water and why the pump was not switching off.
Another comment and not sure which plastic system it is but the one which uses the inserts and uses an olive with a serated edge which locks against the pipe?-these may appear impossible to release but careful use of a fine screw driver and they can be recycled.
Finally if anyones system just refuses to work leaving the pressure pump stood for months can cause the brushes in motor to "short?" across the commutator gap and motor refuses to spin without some initial encouragement. I have had this happen twice after long periods of inactivity. An initial spin of motor plus wiping the commutator and it invariably starts up.
 
Plastic pipe

Hi I am also a plumber/heating engineer. I find that you can remove the HEP fittings by
unscrewing them and cutting the stainless grab ring with a pair of side cutters. The pipe will
go into the speedfit fittings OK but you should use an insert in the pipe ends before
assembly (see your local plumbing shop). Use a little silicone grease for easy assembly.
Don't cut the plastic pipe with a hacksaw, get the proper tool from the plumbing shop it slices the end of the pipe cleanly and gives a good joint. Speedfit are reusable several times if you need to change the pipe runs. Good luck with your project.
 
HBP15 is "Hepworth Barrier Pipe 15mm". Normally good for 12 bar pressure.
The John Guest (JG) white barrier pipe and pushfit fittings as used for central heating would be more suitable, but as other poster says use the white JG pipe inserts as these prevent the pipe from popping out, and prevent the pipe crushing if used on brass compression pittings.
I sometimes use the JG fittings on the grey Polyplumb pipe, never had any problems with this arrangement.
The JG fittings can be removed and reused, so can the grey polyplumb fittings by unscrewing the knurled back part removing the pipe then cutting the pipe just back from the insert sliding of the gripper ring and reassembling the whole fitting noting the correct placing of the gripper and Oring.
The pipe inserts can be removed and reused.
C_W
 
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You can get the stainless locking rings off quite easily if you cut the fitting off and push them off the wrong way.

Use the all plastic Guest Speedfit fittings that will unlock easily, makes maintenance easy.
 
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Are you sure the PRV is the right one for your system. If the pressure of the pump is more than the rating on the PRV then you will not solve the problem. A standard PRV from a plumbers is usually not high enough rating,
 
As other replies have said, you are tackling the problem from the wrong end. First check whether the PRV release pressure is greater than the pump rated pressure. It probably is. Next, check on existing accumulator. If there is one, it should be fitted between the outlet from the pump and the rest of the system. As ststed, the accumulator should never be fitted in the hot pipe. The accumulator may be or the pre-pressurised type and may need inflating with a car or bike (track) pump. A pressure gauge is needed on this pump.

I have never looked at my own pipe fittings in detail, but they are "Hep2O" fittings (that is "hep-two-oh", not "hep twenty".) They are what other posters describe and are de-mountable. With care!

Finally, give us a clue as to where the boat is laid up. There may be one of us with time on our hands who could take a look.
 
Hepworth Pipe Fittings

Hi Folks

Thanks for all the great advice (as usual). Looks like I need to lower myself (or a reluctant volunteer) into the locker that houses the calorifier and take a look at the PRV. I'll ensure that its pressure rating is greater than the water pump. That should at least deal with one issue. I'll also check the cold water accumulator pressure rating.

Wight_Dawn - re where we're laid up - we're not, we're in the water at Largs. We launched on Saturday and had an absolutely stonking circumnavigation of the Cumbraes on Sunday. Decidedly fresh, but very enjoyable.

Thanks again.

Paul
 
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