Posted by: @grantmethestrength

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The pumps on the Grants are beasts mine is on the lowest setting and still shoving 28 L/min through the system on full whack it was shifting over 40 L/min!

@adamk Where is your pump connected to? What pump valves are on the pump? What diverter valve are you using? Vibration in pipes usually comes from valves and the turbulence they cause, not from water flowing through the pipes contrary to popular belief. In Mars's system, the original  primary pipework in to the building has a velocity of nearly 1.9 m/sec, and it is silent.

I did not re-pipe the system, just the plant room, all the original pipework is still being utilised. 

Posted by: @heacol

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Posted by: @grantmethestrength

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The pumps on the Grants are beasts mine is on the lowest setting and still shoving 28 L/min through the system on full whack it was shifting over 40 L/min!

It may be pushing 40l/min, but where is that water going, maybe through the first 2 radiators and very little to the rest?

 

That was one of the issues we were having, the installer kept banging on that the flow rate was really impressive and that we should be amazed by his amazing install! Needless to say we turned it down to the lowest setting and we now actually get a pretty “balanced” heat throughout the house. I need to bite the bullet and get the FRVs and while they are being fitted move the two incorrectly placed rads and finally sort out the last of the leaks in the system while it is drained down! All before it gets cold, when the wife is out so I don’t get in trouble for tinkering again!

@grantmethestrength I am sorry you have not had an optimal service. The FRV valves MUST be installed on the return of the radiators, we had a problem at Mars's because the lockshields were installed both on the flow and returns, so it was not a simple swop out. It is a good idea, when the heat pump is running to identify the flows and returns of the radiators, prior to drain-down, it will eliminate a lot of problems later.

Posted by: @heacol

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@grantmethestrength I am sorry you have not had an optimal service. The FRV valves MUST be installed on the return of the radiators, we had a problem at Mars's because the lockshields were installed both on the flow and returns, so it was not a simple swop out. It is a good idea, when the heat pump is running to identify the flows and returns of the radiators, prior to drain-down, it will eliminate a lot of problems later.

Thanks for the advice Brandon, when I tried (and dramatically failed) to balance the rads last winter I noticed that on some rads the TRVs were on the “wrong”side, but as I am a rank amateur I failed to make a note of which ones so will have to measure them again. Oh well you lives and learns!

Posted by: @heacol

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@adamk Where is your pump connected to? What pump valves are on the pump? What diverter valve are you using? Vibration in pipes usually comes from valves and the turbulence they cause, not from water flowing through the pipes contrary to popular belief. In Mars's system, the original  primary pipework in to the building has a velocity of nearly 1.9 m/sec, and it is silent.

 

I did not re-pipe the system, just the plant room, all the original pipework is still being utilised. 

ok my setup is pretty simple:

7.35kw cibse heat loss

7kw Vaillant Arotherm Plus

no buffers/volumisers

250L Vaillant Heat Pump unistor tank

1 pump in the outside unit.

28mm primaries run to plant cupboard about 5m away from outside heat pump location. the interior sections between the plant cupboard and outside wall were run by my plumber as we were renovating the kitchen and, as Mars will attest i had lots of trouble getting an installer, so needed to get the ceiling up before install day. the pipes are insulated but they have been clipped using single nail plastic pipe clips to the joists. this is what my installer thinks is the cause of the low humming noise like someone left a guitar amp on. i wasnt aware primaries made so much noise and required insulated clips. if i had been told the primaries vibrated i would have run them down the side of the house outside.

i still cant believe its this reason as others have said they cant feel any vibration even when touching the primaries at the back of the HP outside. if i do a hot water run with ECO turned off the vibrations on the outside pipes before the PrimaryPro flexis is quite considerable, after the flexis its maybe half. even in ECO mode if i go in the utility which is about 4m from the entry point of the primaries i can hear the hum near the ceiling and can even feel it slightly if i touch the ceiling.. if i put my ear to the french door double glazed glass inside the house which is about 1m away from the outside unit its like a combination of white noise and the hum.

flow rate is about 750.

diverter valve seems to be a 28mm 3 port Honywell Home 272889

i dont know what to do going forward as no one wants to sort the problems out. Vaillant want to charge me probably to tell me its fine, as other installers have had similar probs with the 7KW and been told by Vaillant all good. the installer seems to want to blame the plumber. im not pulling the floors up to try and re clip the pipes.

on a side note the installer has on numerous occasions told me there sub contractor sparks would come and replace the incorrect and potentially dangerous rcd/mcbs they used due to him not knowing the Vaillant requirements.

@heacol thanks for explaining.  We have FRVs on most radiators.  We have TRVs in the bedrooms instead, but they are all wide open.

The temperature is pretty even throughout the house.  Upstairs is about 1 to 1.5 C higher than downstairs.  

I’m not sure whether that is due to the lack of FRVs, or stratification with warmer air naturally rising from downstairs.  We have a wide stairwell, which enables lots of air flow between floors.

@grantmethestrength, if you pull the trigger on the FRVs, to get 10% off use this discount code at checkout RHHFRV10

Buy them directly from Firepower: https://www.firepowerheating.co.uk/frv

@editor yeah i looked at those but id need 12+ for my place which would set me back £330 for the 12 pack. they look like a underfloor flow rate valve thats been attached to a standard lockshield. im going to see if i can use my thermal camera and or temp meter to balance them first. if not i might have to bite the bullet.

@adamk &@editor I think these FRVs come into their own for professional first installation use

We were very fortunate that our installer did a rough first balance (difficult when OAT was 25C!) and then came back 2 weeks later to tweak them once it was colder outside. But we know from reading the difficulties people had had and described well on this forum, that some installers don’t spend the time getting it right. Balancing ufh is slow because of the time constants.

Any update on this?

It’s been an eventful few weeks, and I want to thank Richard and Chas once again for stepping in. We feel incredibly fortunate to live rurally and yet have two world-class heating engineers on our doorstep. Calm, methodical, pragmatic and meticulous, every decision they make is grounded in proper calculations and clear thinking. No guesswork, no shortcuts, just solid engineering. It took time to undo the issues, but thanks to Richard’s diagnosis and their combined expertise and dedication, we now have heating restored and, more importantly, our confidence renewed in what professionalism in this industry should look like.

This experience has reinforced just how unforgiving heat pump systems are when design and planning are treated as optional.

It has also clarified our next step: in spring we’ll be undertaking a full heat pump retrofix project. The goal is to create a proper blueprint for reconfiguring a system with microbore, long pipe runs and a large footprint. We want to show homeowners and installers not only what bad looks like, but what good looks like, and how thoughtful design, planning and calculation make all the difference.

We’ll be documenting the journey as openly as possible, because there’s no place for guesswork in this sector. This next project is about showing the right way forward so that homeowners can see it for themselves and hold their installers to higher standards.