Webasto Central Heating

[steve_gts]

Hi All,

 

Long story short, I've got a Webasto Thermotop c in place and I'm just about to do the plumbing (pressurised), a couple of questions..........

 

1. Is this a pressure relief valve? http://www.screwfix.com/p/prv-with-gauge-15-x-22mm/41943it says "pressure reducing valve" and I was expecting it to have a third outlet for water to come out of if need be, I can't see where the water would escape from on this one

 

2. Any advice on connecting plastic pipes directly into metal fittings (such as ball valves, or auto air vents) with an olive in?

 

3. I'm planning to use 22mm ID radiator hose from the Webasto to the 22mm plastic spine about 1.5m away, I've (unreliably) been told this can just be clamped to the plastic pipe with jubilee clips, or is there a better way of connecting the 2?

 

Thanks

Steve

 

(i know that was 3 questions, I just got caught up in the moment) :-)

[Joe the plumber]

1. is a pressure reducing valve to reduce the pressure of water going in to it to whatever pressure you set it to. It's not a pressure relief valve, which is designed to open and reduce the pressure in a system when that pressure reaches (or tries to exceed) a pre-set point.

 

If you must use plastic pipe, fit a liner in it when you use a compression fitting on it. If you get a leak, you can use PTFE tape wrapped around the olive (not the screwthread) if tightening it a bit doesn't stop it.

 

Make sure you don't use gate valves for anything, because they're rubbish. Use full bore lever valves instead.

 

Sorry, I nearly forgot. In order to conform to the stereotype, that's fifty quid please....

Edited November 5, 2015 by Joe the plumber

[Saffa]

Hi

 

1. The item you have selected is a pressure reducing valve. This will reduce the pressure in the pipework from one side to the other. You will need something similar to this. You will have to select the correct pressure rating for your system.

 

http://uk.rs-online.com/web/p/pressure-relief-valves/2110430/

 

2. I no expert but I believe you get inserts for plastic pipe.

 

Hope that helps

[Tom and Bex]

3. This is how ours is installed and is one of the few joints that's been completely trouble and leak free. (Tip - don't use the cheapest range of plastic push fit fittings in toolstation, they'll all end up being replaced over a couple of years!)

 

Tom

[NMEA]

3. I'm planning to use 22mm ID radiator hose from the Webasto to the 22mm plastic spine about 1.5m away, I've (unreliably) been told this can just be clamped to the plastic pipe with jubilee clips, or is there a better way of connecting the 2?

 

The correct way to do this is as follows: (22mm heater hose will be too large for the heater outlets that should be 19mm)

2) cut two holes through the bulkhead from engine room to accomodation, insert two 3/4 bsp running nipples with flanged backnuts to secure, on the engine room side fit 3/4 BSPF to 19mm hosetails and connect the correct 19mm hose supplied with the kit from the heater feed and return to them. Fit 22mm x 3/4 BSP JG speedfit stem adaptors to the accomodation side.

You can then either fit full bore valves to them and the 22mm tube to the valves or 22mm tube direct.

This method is robust and reliable and fairly simple to execute.

[steve_gts]

Thanks all.

 

So all in all....................

 

1. Is this a pressure relief valve?

Answer - No, I need the same type that I used on top of the calorifier. (with a 1.5bar setting if I remeember right)

 

2. Any advice on connecting plastic pipes directly into metal fittings...

Answer - PTFE on olives, it's all JG Speedfit with inserts so should be fine

 

3. I'm planning to use 22mm ID radiator hose from the Webasto to the 22mm plastic spine.....

Answer - No, follow NMEA's description above

 

Oh and Joe, if we're doing stereotypes, remember I'm a boater...... can I owe it to you? ;-)

 

Thanks, I'm sure I'll be back again before it's working!

Edited November 6, 2015 by steve_gts

[nicknorman]

PTFE on olives ... Hmmm, sounds a bit of a bodge to me! I've never had a problem with olives onto plastic pipe, provided inserts are used (preferably metal ones). If there is a leak, it's likely due to scratches on the outside of the pipe at the olive, the solution being to check for any scratches when preparing the pipe and ultimately, take care of the pipe before use so it doesn't get scratched

[NMEA]

PTFE on olives ... Hmmm, sounds a bit of a bodge to me! I've never had a problem with olives onto plastic pipe, provided inserts are used (preferably metal ones). If there is a leak, it's likely due to scratches on the outside of the pipe at the olive, the solution being to check for any scratches when preparing the pipe and ultimately, take care of the pipe before use so it doesn't get scratched

Agree with every word except I would substitute "is a complete" for "sounds like a bit of" PTFE tape should be reserved for it's intended use which is BSPT threads.

Should not be used on the stem adaptor or hosetail to running nipple either, use a fibre washer as the threads on those being female are BSPP

[nicknorman]

Agree with every word except I would substitute "is a complete" for "sounds like a bit of" PTFE tape should be reserved for it's intended use which is BSPT threads.

Should not be used on the stem adaptor or hosetail to running nipple either, use a fibre washer as the threads on those being female are BSPP

And of course the other thing is that olives on cheap fittings are brass, which is cheap but relatively hard. Decent olives are softer copper so it's worth getting a bag of copper olives and swapping them out.

[steve_gts]

So can I fit either a speedfit or compression fitting to the stem adaptor? If so could I clamp rubber to it instead? If so I'd like to fit a 22m hose connector inside, so i can run rubber down to where the straight bit's start (which would be much easier and involve no elbows) then just put a stem adaptor there, with the pushfit end to the plastic spine and the rubber clamped to the other end?

 

ALSO A POTENTIAL BIGGIE!

 

The way everything is laid out, it will be so much easier and neater if I add the expansion vessel and water feed into the calorifier loop (the first T off the spine) as that will keep everything in a cupboard (about 1.5M away from the Webasto), the instructions show it all on the main loop immediately before the cold return which would prove quite tricky. Is it likely to cause problems if I do it that way, the rest of it is/will be installed to the letter!

Edited November 6, 2015 by steve_gts

[Joe the plumber]

As far as I'm concerned, PTFE tape used on olives isn't a bodge (however using it on the screwthreads of compression fittings, is). It's a way of stopping leaks from compression fittings where the only other alternative is to replace the pipe (and possibly the fitting) and start again, which can sometimes be very time consuming and awkward.

 

The Professional Standards Inspector who assessed my application to join the Institute of Plumbing (now CIPHE) many years ago picked me up on using it on screwthreads, pointing out that the olive wasn't doing its job if the water had reached the screwthread and it was 'very DIY'. My background in hydraulics was to blame, but it was a useful lesson which has stood me in good stead for many years.

[nicknorman]

As far as I'm concerned, PTFE tape used on olives isn't a bodge (however using it on the screwthreads of compression fittings, is). It's a way of stopping leaks from compression fittings where the only other alternative is to replace the pipe (and possibly the fitting) and start again, which can sometimes be very time consuming and awkward.

 

The Professional Standards Inspector who assessed my application to join the Institute of Plumbing (now CIPHE) many years ago picked me up on using it on screwthreads, pointing out that the olive wasn't doing its job if the water had reached the screwthread and it was 'very DIY'. My background in hydraulics was to blame, but it was a useful lesson which has stood me in good stead for many years.

Are we talking about leaks between the olive and the fitting, or the olive and the pipe? PTFE could surely only address the former since you wouldn't be able to get PTFE under the olive especially once you'd tightened it. I don't really see why there should be leaks between the olive and the fitting unless the fitting was defective. Anyway, using copper olives would solve the problem far more permanently and professionally than a tape bodge.

[Joe the plumber]

I was going to write long reply, but I can't be bothered.

 

To the OP. If you have a problem with a leaking compression joint onto your plastic pipe, and don't fancy having to replace the pipe and/or the olive, wrap a couple of turns of PTFE tape around the pipe/olive (on the opposite side to the nut) and it will help to seal the joint, permanently.

[NMEA]

So can I fit either a speedfit or compression fitting to the stem adaptor? If so could I clamp rubber to it instead? If so I'd like to fit a 22m hose connector inside, so i can run rubber down to where the straight bit's start (which would be much easier and involve no elbows) then just put a stem adaptor there, with the pushfit end to the plastic spine and the rubber clamped to the other end?

 

ALSO A POTENTIAL BIGGIE!

 

The way everything is laid out, it will be so much easier and neater if I add the expansion vessel and water feed into the calorifier loop (the first T off the spine) as that will keep everything in a cupboard (about 1.5M away from the Webasto), the instructions show it all on the main loop immediately before the cold return which would prove quite tricky. Is it likely to cause problems if I do it that way, the rest of it is/will be installed to the letter!

As and answer to the first question, heater hose should not be used on smooth parallel tube, you need either the serrations present or a bulge, if you wish to use heater hose between the two items I suggest you substitute 2 more hosetails for the stem adaptors, that will correctly cover that end. As for the tube interface I suggest you fit 22mm push fit or compression to 3/4" BSP fittings and 2 more hosetails, that will make a secure permanent job of it.

As for the second question, I see no reason not to do as you suggest, pressures in the circuit are equal everywhere so the PRV will still function as it should, as will the expansion vessel. The filling loop is just for filling / repressurising and whilst the return pipe, close to the Webo is an ideal your suggestion will work well enough. One quick point, if you can arrange a bleed point very close to the output hose from the Webo you could save yourself some grief with air locks in the heat exchanger during commissioning and in the future.

[steve_gts]

Thanks NMEA, using the hosetails was my original plan, I just thought the stem adapter might have saved a couple of joins and a few quid, but I'll revert back to hosetails then.

 

Re 2nd point, Phew, that makes it much tidier.

 

When you say bleed point, I assume you mean for air? If so that's OK, I've teed a bottle air vent off the top of the hot outlet pipe about 200mm away from the webasto already, as per the instructions you sent me about a year ago (when I originally planned on getting it done)

 

Thanks,

[NMEA]

When you say bleed point, I assume you mean for air? If so that's OK, I've teed a bottle air vent off the top of the hot outlet pipe about 200mm away from the webasto already, as per the instructions you sent me about a year ago (when I originally planned on getting it done)

 

Yes, that's exactly what I meant Steve, good luck with the install.