ASHP low pressure help pls

[Beelbeebub]

1 hour ago, Dillsue said:

OK, but that's the shower that may need a pump, not a vented cylinder. We're open vented for CH and DHW and have a pump only on an indulgent en suite shower. Rest of house incl a second first floor shower isn't pumped.

You can do that too, or you can pump the whole hot water supply - either way you need a pump. On the plus side newer inverter pumps are pretty quiet and can provide nice even pressure without the old on/off/on/of pulsing behavior of the old ones.

[Beelbeebub]

20 minutes ago, sharpener said:

 

As installed mine had a compliant 22mm D2 setup taken into a first floor soil stack via a Hep2O bladderless trap.

 

Thinking this was where the restriction was I modified it so there was first a 2.5m drop to the ground floor and the trap went into the stack at that level instead.

 

But it is not much better and will still not take the full flow from the tprv. 

 

So I think that the whole concept that the pipe below the tundish needs to be only 22mm - one size up - is flawed, the regulations do not achieve their aim and are pointless. And a tundish hidden away in an airing cupboard slowly filling with water is NFG either.

 

Personally I think it would be better to have the relief valve piped in 15mm directly to waste with an electrical or mechanical alarm to indicate there is something wrong and possibly a small air admittance valve to vent the pipe but prevent smells. 

 

As a further twist the MCS surveillance visit on another house meant the HP installer was called back to move the tundish to somewhere slightly more visible (even though it was pre-existing and not part of his work). The D2 pipe is 28mm bc of the run length but has a 28mm tundish that will overflow too. So the modification is purely cosmetic, the tundish is still in an alcove off a loft above our bathroom, access is still via a ladder and a door which is kept shut so we will neither see or hear any overflow condition. Which is why I test the tprv whenever I am up there, at least I know it is not stuck and the valve seating is washed clean.

 

I think the issue is with air escaping. With a drop you essentially get air locks in the pipe. The water is trying to go down and the air is trying to go up. Paradoxically a bigger vertical might make it worse as there is more back pressure from the air lock before any horizontal section where the air can sit above the water. 

 

The idea of a tundish always confused me. 

 

 

I get there is a reason for them as an anti syphon device and there is a visual indication argument. 

 

Except the visual indication is useless if the thing is in a rarely visited cupboard and the antisyphon argument doesn't seem relevant if the pipe is leading directly outside or even if it's leading to a soil stack.

 

A clear glass section with a properly designed air admittance valve would probably be better albeit more expensive than a tundish. 

[canalsiderenovation]

Will fully update later but have a guy here now from same company whose first question was "who did the service?" Embarassing when I said same company you work for but different guy! This guy seems to know what he is doing been doing it 27 years. Expansion tanks just needed pumping up which he has done and DO NOT need replacing.... paid 50% deposit on the basis they said they needed replacing and guy is going to sort with office.

 

Is sorting that leak (pic I uploaded with the leak from the bottom of Gledhill tank) which he noticed right away. Will explain other stuff later on....

Edited yesterday at 12:09 by canalsiderenovation

[ProDave]

Looks hopeful.  Can't wait for your later update.

[canalsiderenovation]

5 hours ago, ProDave said:

Looks hopeful.  Can't wait for your later update.

 

I spoke to soon. Now we have no heating or hot water and an error code. We had to leave the minute the engineer left as they were 2 hours late. He left the heating and hot water on. Clearly the error code came right after he left as our hot water is 18 degrees and the house is cold.

 

I am absolutely fuming. We are in an even worse position than before. I will be on the phone  to them at 9am in the morning!

 

[ProDave]

 

[canalsiderenovation]

Flow sensor is zero so that is the problem but I can't test any further. Within a few seconds of turning the heating on the error code comes up.

[-rick-]

Whats the pressure reading below the red tank?

[canalsiderenovation]

27 minutes ago, -rick- said:

Whats the pressure reading below the red tank?

Fine.

 

 

When I go to turn on the heating or hot water there is what sounds like a grind noise coming from below (I think the pump thing). 

 

I have sent a scathing email to the company. We are in an even worse position than 24 hours ago. How they have managed to cause more problems I have no idea. We had heating 24 hours ago and even hot water albeit with a leaking tundish. 

Edited 21 hours ago by canalsiderenovation

[-rick-]

4 minutes ago, canalsiderenovation said:

When I go to turn on the heating or hot water there is what sounds like a grind noise coming from below.

 

Looking at your earlier photos, looks like you have a couple of electronic valves down there. Normally make a whirring noise when operated (usually at start/end of a cycle).

 

Given the grinding noise I'm not confident to tell you to try again to try and identify the source of the noise (hopefully others can advise whether it's making things worse to try). But assuming the grinding is coming from a valve then either the engineer removed the head to work on / check the system and didn't refit properly (could be a quick fix) or the valve has failed (strange timing for that given everything else). They can be operated manually which might be enough to get you up an running but wait for someone else with more experience to confirm what to do.

 

My other thought is that if its the CH valve, then its entirely possible that this issue only affects the CH mode and the DHW mode will work. Again wait for others to speak up.

[canalsiderenovation]

Neither heating or DHW is working. I will be on the phone at 9am to the company asking that they either sort it or put everything back to it was when it was working 12 hours ago. 

 

When I attempt to turn either on there is a noise. I am not sure if it is coming from this or the tanks but this was not happening 12 hours ago.

Edited 20 hours ago by canalsiderenovation

[Beelbeebub]

Have they left an isolation valve shut somewhere? Eg the ones usually by the HP outside? 

 

Pretty poor show though. 

[canalsiderenovation]

40 minutes ago, Beelbeebub said:

Have they left an isolation valve shut somewhere? Eg the ones usually by the HP outside? 

 

Pretty poor show though. 

 

What would this look like?

[Beelbeebub]

1 hour ago, canalsiderenovation said:

 

What would this look like?

Honestly, there are too many types to say. 

 

Sometimes they have levers on, or "butterfly" handles, a slot for a screwdriver or sometimes thry are removable so there isn't much to see. 

 

Without wanting to sound mean, if you have to ask, you probably need to wait until tomorrow morning and get the engineer out.  

 

It wouldn't be the first time an engineer has left a Friday job forgetting to turn a critical bit of of equipment back on. 

 

Good luck. 

[Russdl]

3 hours ago, canalsiderenovation said:

When I attempt to turn either on there is a noise

Holy sh*t, and what a noise, has he left a spanner in the pump??

 

I’m sorry I can’t help in any way, but do go in all guns  blazing tomorrow. 

[canalsiderenovation]

1 hour ago, Beelbeebub said:

Without wanting to sound mean, if you have to ask, you probably need to wait until tomorrow morning and get the engineer out.  

 

It wouldn't be the first time an engineer has left a Friday job forgetting to turn a critical bit of of equipment back on. 

No, not mean at all because I have no idea what I am looking at and better leave it to the 'experts' although at this point I'm questioning if the 'experts' actually know anything.... 

[canalsiderenovation]

The same guy from yesterday came out. The filter was blocked (this bit).

 

 

He said he did test it before leaving but obviously more crap got in it. He has shown me exactly what to do to check the filter now for future.

 

The rattling sound is actually the coil at the bottom of the Gledhill tank. He has adjusted the flow etc and its 18.2lpm. There is a little rattle and he showed me if you apply a bit of pressure to the top and bottom pipes it stops. I'm still not sure why we have this now and didnt before. He has used zip ties to apply this pressure. Not ideal but for now we have heating and hot water. I think perhaps in the long term we need to get someone else out as I don't know why we have had no rattle for years and now do. He did say you can fit a valve/additional pipework.

 

Going back to yesterday. The issue with the tundish was all to do with the pressure issues and there was quite a leak from here which needed tightening. He said that was likely the cause of the pressure drop and subsequent issues.

 

 

The expansion tanks did not need replacing, just pumping back up.

[ProDave]

Lets hope it continues to work.  Keep us posted.  I hope they reduced the bill somewhat as they didn't need to replace the expansion vessels.

 

Re the rattling sound.  I had this with my Telford cylinder.  There seems to be a conflict that a heat pump demands a very fast water flow rate, that makes the coil inside the tank vibrate and rattle.  If you reduce the flow rate so the tank is happy, the rattling stops but the heat pump has a hissy fit because the flow rate is too low.  In my case I had an automatic bypass valve which is really there to cover the time the motorised valves take to open.  It took a lot of fiddling with the settings on the bypass valve to essentially make it bypass all the time just to keep the heat pump flow rate happy and reduce the flow going through the cylinder.

[canalsiderenovation]

7 minutes ago, ProDave said:

I hope they reduced the bill somewhat as they didn't need to replace the expansion vessels.

 

I haven't had the bill yet.

 

I am annoyed they had to come out again. I think really he should have stayed long enough to see the filter was not blocked. He said he did check and left the heating and hot water on when he left but it was clear from the water temp and cold house that the error code must have appeared pretty much right after he left, preventing the heating and hot water coming on.

 

8 minutes ago, ProDave said:

I had this with my Telford cylinder

Yes the engineer mentioned he has seen this on Telford cylinders before but less so on Gledhill.

[sharpener]

3 hours ago, canalsiderenovation said:

He said he did test it before leaving but obviously more crap got in it. He has shown me exactly what to do to check the filter now for future.

 

The rattling sound is actually the coil at the bottom of the Gledhill tank.

 

Those inline filters get blocked quite easily.

 

In slow time it would be better to bin it and get a Magnaclean or Adey HP filter fitted indoors, they have a much bigger element like an enormous kettle fur collector and a magnet for collecting magnetite particles shed by the radiators - which you should not be gettting if there is adequate inhibitor in the system.

 

Gledhill cylinders have a bit of a reputation for noisy internals, I have seen it reported as a specific quality control issue in the factory.

[Bramco]

19 minutes ago, sharpener said:

Gledhill cylinders have a bit of a reputation for noisy internals, I have seen it reported as a specific quality control issue in the factory.

Maybe all cylinders - we've got a Newark that is pretty noisy.....   I've always put it down to the coil being corrugated and trapping air - and we haven't got round to putting in anything to get rid of the air yet - next summers job.

[Nickfromwales]

In the Telford MI’s, cylinders over a certain size have instructions to bridge the cylinder flow and return tappings together with a simple inline gate valve (iirc) to allow a permanent, adjustable bypass to take this bump out of the road.

 

I wonder if the engineer upped the pump speed, in an attempted to combat the frequency of the low flow issue, eg giving the ASHP access to a bit more throttle; this would account for why you had no cylinder noise issue before.

 

I strongly dislike these filters as they have such low capacity for functioning when these even a slight build up of crud.

 

@canalsiderenovation Get a larger mag filter installed, like a Fernox TF1 or an Adey Magnaclean for easy life going forward. This one will keep blocking prematurely afaic.

 

I'd also ask specifically if the pump speed had been increased and that’s what has caused the cylinder rattle. 

[canalsiderenovation]

1 hour ago, Nickfromwales said:

I wonder if the engineer upped the pump speed, in an attempted to combat the frequency of the low flow issue, eg giving the ASHP access to a bit more throttle; this would account for why you had no cylinder noise issue before.

 

Yes I suspect so.

 

1 hour ago, Nickfromwales said:

I strongly dislike these filters as they have such low capacity for functioning when these even a slight build up of crud.

 

@canalsiderenovation Get a larger mag filter installed, like a Fernox TF1 or an Adey Magnaclean for easy life going forward. This one will keep blocking prematurely afaic.

 

Strangely we have had no issues with the filter up until now and now I know what to do I feel confident regularly checking it. Kind of a bit like the mesh thing on our kitchen Quooker tap. I will definitely look into this though and getting one of those clear tundish things too which the engineer suggested. I probably won't use this same company again though so will need to find another company/competent person... and that is a struggle!