Bypass Valve passing

[need2 knowmore]

I have recently had a new Boiler fitted, it required an Auto Bypass Valve to be fitted. A Honeywell DU145 was fitted and left on setting 1 it was open all the time. The plumber said it could not be set until all the new Radiators had been installed. The system is on an S plan with 2 valves so at present it is only pumping through the Cylinder coil. I looked at the Honeywell installation sheet and from the Boiler min flow requirement and the pump curve, I calculated that the valve neede to be set at 3.5., but even at this setting it still was open and passing. I even set it at 6 and it still passed. I called the plumber back and he said it was ok and could not be set until the heating circuit was complete. I agree that it may need to be adjusted when the Heating circuit it complete and balanced and the pump set at the setting and may be on a different curve, but I cannot understand why the valve passes when on just the H/W circuit. The H/W piping run is short between the Boiler and the Cylinder with only a few bends and a S valve so the back pressure cannot be high.
Am I right in thinking something is wrong, or am I missing something ?

 

[galaxy_plumbing]

could be faulty auto-bypass valve. I would leave it to plumber and if he finds it faulty then he replaces it

 

[Doodlebug]

could be faulty auto-bypass valve. I would leave it to plumber and if he finds it faulty then he replaces it

Yeh I agree, don't play with it or he may say you've knackered it. Lol

 

[need2 knowmore]

I am not very confident in the plumber since he said the valve was ok even though it was passing.

 

[need2 knowmore]

Thanks, see my reply to doodlebug

 

[galaxy_plumbing]

well, we all are just a human, maybe he just didn't like too many questions that time..I wouldn't worry, however if you in doubt, you can still call other engineer or can't you?

 

[doitmyself]

Has it been fitted the correct way round? The arrow on the side should point away from the pump.

 

[GasmanxxxR1]

the by pass is designed to open when the system becomes restrictive (like when a 2 port valve closes) if your pump is just pumping around the hot water circuit then thats quite a restrictive circuit. So the valve is opening to maintain a certain flow rate around the boiler.

Is the boiler working okay?

Do you Have hot water?

 

[need2 knowmore]

Thanks for your reply,the boiler is working OK and the water is hot.
I did not think that the valve would open unless the circulation was severly restricted, like both 'S' valves closed on when C/H only all rad valves closed.

 

[Roger Welton]

Was the system flushed when the boiler was replaced, could be some muck stuck under the seat of the bypass valve.

 

[PETE 123]

You cant beat a good old gate valve as a by-pass

 

[AWheating]

when the system is finished your plumber when setting it up correctly can test to see if its faulty, if you dont think your plumber know what hes/shes doing then speak to your plumber about your concerns face to face. We cant pass comment on his/hers ability really.

 

[DirksPlumbing]

You cant beat a good old gate valve as a by-pass

I am wondering if these will get a renaissance with the upcoming need for A rated pumps as you need to have them sitting on the constant pressure profile in order to deal with ABVs which in return means that it does not work in its most efficient way.
Just wondering how the lift of return temperature could be minimized without an ABV.
Possibly something like a micro gate valve or even a requirement for 3 port valves?
But then zoning via 2 port valves becomes a bit a nuissance.

@need2 knowmore: Indeed it would possibly easier for you as well to let the man do his work and get things sorted that are not satisfactory once your plumber tells you it is finished. No matter how good or bad is someone, there are times when you have to weigh between a perfect system tomorrow or hot water at least today.

But I agree as well it should not pass through if the hot water circuit is open. Have you made sure that the valve was open indeed all the time otherwise there could have been a wanted pass through and it takes a while for cooling down anyway.
If so it could be grid or even a piece of solder. At the point of flushing the system most issues would get sorted anyway.

Hope everything turns out to your satisfaction without too much hassle and efforts for you.

 

[doitmyself]

I am wondering if these [gate valves] will get a renaissance with the upcoming need for A rated pumps as you need to have them sitting on the constant pressure profile in order to deal with ABVs which in return means that it does not work in its most efficient way.

Grundfos recommend a Tacanova Setter flow control valve in series with the ABV. This will set the maximum flow through the bypass circuit when the ABV opens.

See Bypass Commissioning Alpha 2 or 2L

 

[DirksPlumbing]

Grundfos recommend a Tacanova Setter flow control valve in series with the ABV. This will set the maximum flow through the bypass circuit when the ABV opens.

See Bypass Commissioning Alpha 2 or 2L

That answered my question to the spot.
"An automatic bypass valve should not be used with the Alpha2 pump in proportional pressure control."
When you look at the pump curve you will see that there is no physical way to set up an ABV to a working setting. Just should have included the 15/60 as well in the diagram. One can definitely safe that money for a Flow adjuster.

But then again according to the diagram it should be impossible to set up for the constant pressure as well. But I can confirm that it works perfectly fine. The pressure increases quite a bit towards 0 flow. Enough for opening the ABV. Got some working like that flawless for over a year. Any malfunction of the setup would have meant a call out because of instant overheating on those systems. Have not had one yet. And the customers are over the moon with the savings in electricity. Applies to the Alphas as well as to the Magna.

Not sure how effective these are for small systems as I hardly get any feedback from there. Suppose there is not such a high percentage of electricity used for the heating anyway.

 

[need2 knowmore]

My Pump is a Grundfoss Selectric 15-60 currently running on setting 2.From the pump curve and the boiler min flow requirement, I calc that the ABV should be set at 3.5.
I am getting conflicting messages, some say the valve will be open when just the H/W circuit only is on, others say it should not be open. This confuses me since I thought the purpose of the ABV was to ensure that the flow through the boiler never fell below the min flow when the boiler was on. The main reasons for this to happen I thought, was if both 'S' valves were closed or all Rad valves were closed when C/H only. I find it hard to see how just pumping through the H/W cicuit only would cause the flow to fall below the min. flow.

 

[chris watkins]

I have re-wired my old s plan so it has priority hot water which closes the heating valve, at all other times heating valve is open to allow heat to be dissipated from boiler as required, In that way no requirement for ABV on system with Alpha2 (I have got W.Compensation) . I can see us going back to divertor valve on new installations. to overcome this. It will be fun when the pump directive comes in on 1st Jan 13, still always got Pete's option to break building regs L "You cant beat a good old gate valve as a by-pass" ignorance is bliss isn't it !! LOL

By the sounds of it Need2 the ABV should not have been installed !! What boiler have you got??
Sorry did not see last post !! 15/60 installed.

 

[need2 knowmore]

The Boiler is a Vaillant ecoTECplus428 open vent boiler and they require an ABV to be fitted.

 

[peteheat]

My Pump is a Grundfoss Selectric 15-60 currently running on setting 2.From the pump curve and the boiler min flow requirement, I calc that the ABV should be set at 3.5.
I am getting conflicting messages, some say the valve will be open when just the H/W circuit only is on, others say it should not be open. This confuses me since I thought the purpose of the ABV was to ensure that the flow through the boiler never fell below the min flow when the boiler was on. The main reasons for this to happen I thought, was if both 'S' valves were closed or all Rad valves were closed when C/H only. I find it hard to see how just pumping through the H/W cicuit only would cause the flow to fall below the min. flow.

Let the man finish the job, if you have questions ask them then.

I know if I was doing your job and saw this thread I would not finish it, can't understand why people employ someone then continuously second guess their work.

Cheapest quote maybe?

Not GSR?

An apprentice doing a homer?

If you are paying a professional let him get on with his job.

 

[need2 knowmore]

Thanks for the reply, I did'nt do the job because of the gas work, I am a retired engineer who understands hydraulic system and am quite capable of doing all the water side of the work, I have sized and installed a few C/H systems, but now I prefer to pay someone to do the job. The plumber was not the cheapest and he had to get someone in to do the gas side. It is just that I am not sure he knows what the ABV does and how to set it up. I have never had to fit an ABV in any C/H system, but my knowledge of relief valves makes me question the operation of this ABV so any help from experienced C/H enginners/plumbers would be most welcome. I did call the man back and he said the valve was OK even thoughit was passing.
Please see my earlier post on this problem for more info.

 

[peteheat]

The valve is designed to pass if any of the zones are satisfied, the pump continues to circulate at the same rate so as each 2 port closes the ABV opens to prevent the pump coming under pressure.

I know some plumbers prefer to allow the valve to pass even when all the zones are open, a reason for this can be if the pump is not strong enough to circulate at setting 1 but a little too much at setting two so to compensate the ABV is allowed to pass as this gives a well balanced system.

 

[GasmanxxxR1]

If the boilers working fine and you've got hot water. What do you care?

 

[need2 knowmore]

Three reasons to care.
i. The recovery time for the cylinder will be extend.
2. When the C/H is on in cold weather, the Maximium output of the Boiler will not be available if a significant amount of heat is pased back to the Boiler through the open ABV.
3. The ABv should not be passing all the time.On an 'S' valve system, it should only open if both the C/H and the DHW valves are closed. Some of the Radiators or the C/H circuit do not have TRVs so it is unlikely that the ABV will be required to open
when on C/H circulation only.
I am only trying to get an informed view on a problem and not out to 'ball out' the plumber who does not seem to understand the problem.

 

[TBServices]

Three reasons to care.
i. The recovery time for the cylinder will be extend.
2. When the C/H is on in cold weather, the Maximium output of the Boiler will not be available if a significant amount of heat is pased back to the Boiler through the open ABV.
3. The ABv should not be passing all the time.On an 'S' valve system, it should only open if both the C/H and the DHW valves are closed. Some of the Radiators or the C/H circuit do not have TRVs so it is unlikely that the ABV will be required to open
when on C/H circulation only.
I am only trying to get an informed view on a problem and not out to 'ball out' the plumber who does not seem to understand the problem.

There IS no problem until he's finished the job and balanced the system. If you were stood over my shoulder asking questions all the time, I would fob you off in a way that would get you to leave me alone the fastest. It seems your plumber has elected to plead ignorance.


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[DirksPlumbing]

Some of the Radiators or the C/H circuit do not have TRVs so it is unlikely that the ABV will be required to open
when on C/H circulation only.

If you have not fitted TRVs on all radiators then you are gonna simulating an open ABV throughout the heating period anyway. Your passing ABV might be the least problem as by now we do not know the pass rate.
The fact it gets hot is not a measurement telling more than an indication.
If the pass rate on the ABV is minimal then your TRVless rads will do the same far worse unless turned off completely. Of course only at heat demand but seeing your boiler there will be plenty of that unless it is way oversized.
The only exemption should be the room/s with the room thermostat/s.