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Thread: New Evohome plumbing issues

  1. #1
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    Default New Evohome plumbing issues

    Hi,

    I've been reading this forum for a while and read lots before having my Evohome installed. Getting it installed was a mission in itself, but that's another story. Anyway, as far as I understand (and my understanding is limited, so please accept my apologies), my system is installed correctly and a quick snapshot is as follows:

    S-Plan system - stored hot water, zone valve for UFH and HW. All radiators fitted with HR92 controllers. ABV fitted next to boiler. New boiler and unvented cylinder installed along with one additional radiator. From an Evohome perspective, I think everything is functioning as it should. Zones start/stop and follow the schedule as I expect. There are some minor niggles, but nothing that isn't documented on here already.

    My issues are plumbing related. I appreciate this forum is about heating control, but if anyone can offer advice, that would be helpful.

    Issue no.1
    My system has a fair bit of air in it following installation and so to resolve this, I have been removing the HR92's and ramping the system up for 30 mins odd and then allowing to cool before bleeding. The system still has air in it despite bleeding the radiators many times. Whilst doing this, I noticed that two radiators (porch and study) do not get hot at all. After doing some investigation, I found that a branch situated within a wardrobe went from hot to cold at an elbow. My plumber suggested there may be an airlock and so after refitting the HR92's, I sent heat only to the two affected radiators and they worked as expected.

    Last night, I tried firing up all rads again using the aforementioned technique and again the porch and study rads did not get hot at all. Do you think there is an airlock, or is it that the system needs to be better balanced to allow water pressure to reach these two radiators? The fact that a pipe went from hot to cold with no obvious reason I guess would suggest an airlock. Why would this keep happening? In normal usage situations i.e. when heating zonally, this doesn't occur, it only seems to be when ramping up all rads that it is an issue. Surely this is crucial for effectively removing air from the system though?

    Issue no.2
    My second issue is much more irritating. The pipe entering the HR92 side of one of the landing radiators vibrates intensely for about 2-3 minutes numerous times during the middle of the night (and in the day). My (uneducated) opinion is that when this happens, the boiler is still running and the rest of the HR92's are closed or thereabouts and this build up of pressure causes the vibration. Opening the HR92 on this particular radiator alleviates the issue and last night I ended up leaving it 3/4 open (and red hot) until morning so that we could sleep. This radiator would usually be off overnight. This stop gap solution isn't ideal, as due to aforementioned air in the system, the radiator isn't as discreet as it could be at 3am when warm water is being pumped around.

    My understanding is that the ABV should release this additional pressure caused in situations where all valves are closed? I have a Honeywell ABV and set to 0.3/0.4 (as I understand is about right), which makes no difference.

    Can anyone offer any advice on these issues? It's tricky to keep hassling my plumber, as he is a family friend and has two kids of his own and I don't want to trouble him. I've already been in contact about lots of smaller niggles. If remedial work is needed, I will of course contact him, I just want to see if it's something I'm doing wrong before bothering him again.

    Thanks

  2. #2
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    Quote Originally Posted by Tempted View Post
    Issue no.1
    My system has a fair bit of air in it following installation and so to resolve this, I have been removing the HR92's and ramping the system up for 30 mins odd and then allowing to cool before bleeding. The system still has air in it despite bleeding the radiators many times. Whilst doing this, I noticed that two radiators (porch and study) do not get hot at all. After doing some investigation, I found that a branch situated within a wardrobe went from hot to cold at an elbow. My plumber suggested there may be an airlock and so after refitting the HR92's, I sent heat only to the two affected radiators and they worked as expected.

    Last night, I tried firing up all rads again using the aforementioned technique and again the porch and study rads did not get hot at all. Do you think there is an airlock, or is it that the system needs to be better balanced to allow water pressure to reach these two radiators? The fact that a pipe went from hot to cold with no obvious reason I guess would suggest an airlock. Why would this keep happening? In normal usage situations i.e. when heating zonally, this doesn't occur, it only seems to be when ramping up all rads that it is an issue. Surely this is crucial for effectively removing air from the system though?
    I very much doubt that it is an air lock. If you were able to get those radiators flowing hot by closing all the other radiators any air lock would have been pushed out of them by now. (And I assume the radiators themselves have been bled as well)

    It will be a balancing issue - most likely none of the radiators have been balanced. I've seen systems where no attempt has been made to balance them, relying on TRV's closing on some radiators for others to get heat. Do a thorough balancing of the lockshield valves on all the radiators (it can take a few hours if you're a perfectionist!) and that should sort your problem. It might also be a sign that there is some restriction inside the pipes to those radiators like limescale buildup, in which case balancing will only help so far as balancing just restricts the flow of the easier flowing branches to more accurately match the branches that are more restricted or have longer runs.

    Issue no.2
    My second issue is much more irritating. The pipe entering the HR92 side of one of the landing radiators vibrates intensely for about 2-3 minutes numerous times during the middle of the night (and in the day). My (uneducated) opinion is that when this happens, the boiler is still running and the rest of the HR92's are closed or thereabouts and this build up of pressure causes the vibration. Opening the HR92 on this particular radiator alleviates the issue and last night I ended up leaving it 3/4 open (and red hot) until morning so that we could sleep. This radiator would usually be off overnight. This stop gap solution isn't ideal, as due to aforementioned air in the system, the radiator isn't as discreet as it could be at 3am when warm water is being pumped around.
    Almost certainly this is "water hammer" from an incorrectly installed valve body. Sounds like you have old fashioned uni-directional TRV valve bodies and this one is installed on the wrong side of the radiator. Is the HR92 on the flow or return side of the radiator ? Which way does the arrow point on the valve body, does it point in the correct direction from flow to return ?

    Generally if you have the valve body upright (HR92 up the right way) a uni-directional valve body must be installed on the colder return flow side. If it's on the wrong side it will hammer/chatter/vibrate when the valve is open just the right amount.

    You have two possible solutions - swap the valve body and lock shield valves on the radiator over so the valve is flowing the right way, or replace it with a bi-directional valve that can work either way. (They have double arrows pointing in both directions)

    Either requires a drain down of course.
    My understanding is that the ABV should release this additional pressure caused in situations where all valves are closed? I have a Honeywell ABV and set to 0.3/0.4 (as I understand is about right), which makes no difference.

    Can anyone offer any advice on these issues? It's tricky to keep hassling my plumber, as he is a family friend and has two kids of his own and I don't want to trouble him. I've already been in contact about lots of smaller niggles. If remedial work is needed, I will of course contact him, I just want to see if it's something I'm doing wrong before bothering him again.

    Thanks
    0.3 to 0.4 bars on the ABV sounds fine - I run mine at 0.4.
    Last edited by DBMandrake; 8th November 2016 at 10:12 AM.

  3. #3
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    Issue-1 sounds like a balancing problem.
    Issue-2 have you tried turning down the ABV setting?, so that it opens earlier?

    Before I had the ABV fitted, my system when all HR92's were closed, would try to pump across no-load (radiators shut) and through the by-pass gate valve, this created a vacuum at the pump inlet and sucked in air via the vent pipe, then the system would start flowing and it meant one radiator kept filling with air, the ABV cured all that. It does sound like yours is set at too high a pressure.

    Also if you have a variable speed pump, try turning it down to the minimum speed as a starting point.

  4. #4
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    Thank you both for taking the time to reply. I've seen you both participate in numerous threads I have read.

    Quote Originally Posted by DBMandrake View Post
    ...It will be a balancing issue - most likely none of the radiators have been balanced. I've seen systems where no attempt has been made to balance them, relying on TRV's closing on some radiators for others to get heat. Do a thorough balancing of the lockshield valves on all the radiators (it can take a few hours if you're a perfectionist!) and that should sort your problem. It might also be a sign that there is some restriction inside the pipes to those radiators like limescale buildup, in which case balancing will only help so far as balancing just restricts the flow of the easier flowing branches to more accurately match the branches that are more restricted or have longer runs.
    I wondered if this might be the case. My plumber power flushed the system and so hopefully there is a minimal amount of crap inside the pipes. He pretty much rolled his eyes at my suggestion that it needed balancing - thought I'd been reading too much on forums like this. Your comments have made me realise I really should spend the time doing it. I made a start last week and know how many turns each valve has etc so can now turn them up/down in a more controlled way. What I don't have though are thermometers - did you buy some when you did yours?

    Quote Originally Posted by DBMandrake View Post
    Almost certainly this is "water hammer" from an incorrectly installed valve body. Sounds like you have old fashioned uni-directional TRV valve bodies and this one is installed on the wrong side of the radiator. Is the HR92 on the flow or return side of the radiator ? Which way does the arrow point on the valve body, does it point in the correct direction from flow to return ?

    Generally if you have the valve body upright (HR92 up the right way) a uni-directional valve body must be installed on the colder return flow side. If it's on the wrong side it will hammer/chatter/vibrate when the valve is open just the right amount.
    I had them all replaced with Honeywell Valencia bi directional bodies and so presume this cannot be the issue?

    Quote Originally Posted by DBMandrake View Post
    You have two possible solutions - swap the valve body and lock shield valves on the radiator over so the valve is flowing the right way, or replace it with a bi-directional valve that can work either way. (They have double arrows pointing in both directions)
    Am I right to say that lockshield valves are always bi directional and so that would not be my issue?

    Quote Originally Posted by DBMandrake View Post
    0.3 to 0.4 bars on the ABV sounds fine - I run mine at 0.4.
    Quote Originally Posted by g6ejd View Post
    ...
    Issue-2 have you tried turning down the ABV setting?, so that it opens earlier?

    Before I had the ABV fitted, my system when all HR92's were closed, would try to pump across no-load (radiators shut) and through the by-pass gate valve, this created a vacuum at the pump inlet and sucked in air via the vent pipe, then the system would start flowing and it meant one radiator kept filling with air, the ABV cured all that. It does sound like yours is set at too high a pressure.
    I tried turning it down to 0.3 whilst it was actually happening and it didn't appear to make any difference. I didn't want to go too low as I wasn't sure what impact this may have, seeing as it is meant to be set semi-scientifically. Although most comments I've read by plumbers don't seem too concerned about the minimum flow rate approach detailed in the ABV manual. Is there any harm in turning it right down to say 0.1 or 0.2 to see if that helps?

    This could explain why I am never able to get all of the air out of the system though if what you're saying is correct.
    Last edited by Tempted; 8th November 2016 at 10:58 AM.

  5. #5
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    On my system the pump inlet has a feed from the HTG header tank and an expansion pipe. When the pump started (on high speed) it immediately drew in air, that being the path of least resistance over the water, we suffered from cold and noisy radiators for a while until the ABV was fitted, now all the noise and air has gone. If you make a note of where it is currently adjusted to, then adjusting for a test does not sound like an issue because you can return it back to its origin setting. Turning it down has the effect of by-passing the radiators sooner so giving the boiler water flow.

    It sounds like the ABV is not opening when there is insufficient flow through the 'errant' radiator and it should do to reduce the pressure that's causing the vibration. That tells me it needs reducing to say 0.2 or less, if it were me that's what I would do. Plus is the lock-shield valve on the radiator open enough?

  6. #6
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    Quote Originally Posted by g6ejd View Post
    On my system the pump inlet has a feed from the HTG header tank and an expansion pipe. When the pump started (on high speed) it immediately drew in air, that being the path of least resistance over the water, we suffered from cold and noisy radiators for a while until the ABV was fitted, now all the noise and air has gone. If you make a note of where it is currently adjusted to, then adjusting for a test does not sound like an issue because you can return it back to its origin setting. Turning it down has the effect of by-passing the radiators sooner so giving the boiler water flow.

    It sounds like the ABV is not opening when there is insufficient flow through the 'errant' radiator and it should do to reduce the pressure that's causing the vibration. That tells me it needs reducing to say 0.2 or less, if it were me that's what I would do. Plus is the lock-shield valve on the radiator open enough?
    Thanks again for the advice. I'll happily try it on a lower setting if there is no damage to be done.

    How would one know if it is open 'enough'? The radiator itself gets very hot, so does that answer the question, or is it more complicated than that? It certainly sounds plausible that there is air being drawn in anyway.

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    Sorry, I should have explained cold radiators because they were full of air. All that opening the ABV up or allowing to open at lower pressure will do is send hot water back to the boiler inlet, not efficient but for the purposes of a test maybe worth doing. You should be able to feel either side of the ABV to tell if water is already flowing as temperatures will be near identical to the touch, but if the pipes between flow are return and ABV are very short then conduction of heat will make this near impossible to discern as they will be hot with no cross-flow.

    For radiator balancing I use one of these: http://www.screwfix.com/p/titan-infr...IrFxoCT8Tw_wcB

    It does not have to be accurate but most are within +/-1C because it's a differential measurement so in relative terms the difference is al that matters, I set mine to 12C difference flow and return, but it's not easy to do as eventually the whole system warms up. I found I had to reduce pump speed to the minimum to allow the heat to be dissipated from the radiators as part of my balancing act. If you know the radiator manufacturer they usually state the differential temperature for maximum heat output-efficiency.

    I suppose a rule-of-thumb is if the differential (flow-return) temperature is less than 10C then it needs balancing by closing the lock-shield valve (LSV) 0.5-turn at a time. I know its teaching granny to suck eggs, but I found keeping meticulous notes of each radiator setting and temp-diff invaluable and ideally start the process when the heating starts and quickly determine which radiator comes on first to get an order of heat up - then those that warmed up first have the least resistance and need their LSV to be adjusted.

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    Quote Originally Posted by g6ejd View Post
    For radiator balancing I use one of these: http://www.screwfix.com/p/titan-infr...IrFxoCT8Tw_wcB
    This is my tool of choice: https://www.amazon.co.uk/d/Electroni...words=flir+one

    Picked one up for 150 as a Lightning Deal - I expect they'll be that price again on Black Friday.

    P.

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    Ah yes, the ultimate choice, I want one now, I've not seen these before... Being able to see a thermal image of say a room or radiator gives a different dimension plus many other uses, so I'm standing by for Black Friday now

  10. #10
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    The alternative is the Seek Thermal. Here's a few words I wrote about them in my PC Pro column recently:

    Let’s start this month by looking at smartphone based thermal imaging, as things have now moved on considerably since in the year since I last covered the subject in this column.

    Back then, you could either get a FLIR One which was a strange device, being built into a special case that only worked with the iPhone 5 or 5S. Or you could get the Seek Thermal which was a little plug-in dongle that worked with any Android or iOS phone (or indeed tablet). The Seek Thermal also had a higher resolution camera, so given the two systems were pretty much the same price it was an easy win – a year ago the Seek Thermal camera was the thermal imaging camera to buy.

    So what’s happened in the intervening months? Well, FLIR has brought out a new camera which attaches to the Micro USB socket on Android phones or the Lightning socket on iPhones. It also has a higher resolution, so in both respects it is now a closer match to the Seek Thermal. Annoyingly though, this new camera is still called FLIR One, despite it being completely different to the previous FLIR One. I’d have thought there was a pretty obvious name for a follow-up to something called ‘One’, but what do I know… On the various thermal-imaging-nerd forums it’s usually referred to as the F1G2 (being short for FLIR One generation two).

    Meanwhile the Seek Thermal camera has been renamed Seek Thermal Compact, but it’s exactly the same product as before. The name change is because the company has also released a standalone device with a screen, not requiring a smartphone. The move to the ‘Compact’ moniker is simply a marketing exercise, to help differentiate between these two product lines. It’s pretty much like both companies are going in opposite directions – FLIR started with standalone devices and moved into mobile, while Seek seems to have done the reverse.

    Now that we have two comparable products, though, I thought it might be worth looking at them both, and seeing with the Seek Thermal camera still has the edge.

    As I’ve already described, physically they are both very similar, plugging into the socket on the bottom of your phone. The Android version uses Micro USB, so if you have one of the newer phones with a USB-C connector you’ll need to use an adaptor. Likewise, because Micro USB has a right and wrong way round (unlike Lightning and USB-C) there’s a chance that your phone and the camera might both be pointing in different directions. FLIR supplies a useful adaptor with its camera that reverses the Micro USB port – it’s something that Seek Thermal users would probably kill for, because their camera won’t have been supplied with an adaptor, and none of these suggested as additional third part purchases by Seek are as neat as the one on the FLIR box.

    The Seek Thermal Compact is a bit smaller than the FLIR One, although in use the size isn’t an issue. The Seek runs off the phone’s battery, while the FLIR has an internal battery that needs to be charged – I’ve found it usually lasts around 45 minutes, so fine for most jobs.

    Both cameras present the usual thermal imaging pictures that I’m sure you’ll all be familiar with (the colour palate these use is called ‘Iron’), and both allow you to take spot temperature measurements from points within that picture.

    They both take a slightly different approach when it comes to imaging. The Seek Thermal Compact uses a 206x156 pixel thermal sensor. The FLIR One’s sensor is 160 x 120 pixels. So you’d assume that the former would have better image quality, but you’d be wrong. The FLIR has a VGA camera sitting alongside the thermal imager, and using a system that FLIR calls MSX it creates a composite image from both sensors. MSX apparently stands for “Multi Spectral Dynamic Imaging” – nope, me neither!

    You might expect the system would simply take a monochrome image from the VGA camera and then ‘colour it in’ using the thermal imager. Although that would probably work OK, the MSX system is clever than that. It does edge detection using the VGA camera, and then overlays these lines on the thermal image.

    It works brilliantly well, and as you can see from the example images on this page, it results in the FLIR One delivering a much clearer image than the Seek Thermal Compact, despite the latter having a higher resolution thermal sensor.

    Both cameras use an app to access the camera, and although there are differences they both end up doing pretty much the same thing. Another difference between the two devices is that the Seek Thermal makes a noticeable clicking noise. This is something inherent in all thermal imaging cameras – a ‘blade’ is pushed in front of the thermal sensor as it needs to frequently re-calibrate. The same happens with the FLIR One, but the noise is pretty much inaudible unless you put your ear very close to the device.

    As well as the aforementioned Micro USB reverser, the FLIR also comes with spacers which allow you to mount the camera firmly to a phone, whether the handset is in a protective case or not.

    Both cameras come with carrying cases, but the Seek Thermal one is water and dust proof, whereas the FLIR case is really more of a protective cover.

    OK, so apart from the ‘cool gadget’ factor, are these things actually useful? Do they have any purpose beyond making weird looking profile pictures for Facebook? Well I guess that depends on your needs, but I’ve certainly used mine several times. At home I knew there were pipes running across a concrete floor, feeding a distant radiator, but I wasn’t sure exactly where they were. With a thermal imaging camera I was able to spot the pipe run straight away.

    Likewise, using a thermal imaging camera I’ve been able to determine an area in my loft where the insulation needs adjusting (it shows up as cold in winter and warm in summer). Oh, and it’s utterly brilliant at cheating if you want to beat your kids at kids and seek!

    In a small business environment, a thermal imaging camera is a great way to spot equipment that isn’t energy efficient, as it’ll show a raised temperature compared to its surroundings. You can even use it to detect future HDD problems in a storage array, as failing drives will almost always show a slightly higher temperature than their neighbours. A monthly walk through your server room looking for hotspots could end up anticipating failures and saving you lots of time and a money – perhaps even preventing lost revenue.

    For trades people one of these cameras could also be a great addition to their tool box. A surveyor could use one to gauge the thermal efficiency of a building, or whether a tank had adequate lagging. And for plumbers the camera shows at a glance whether radiators are sludged up meaning that the central heating system needs to be power-flushed. I know that heating engineers often struggle to convince home-owners that this needs doing, but to be able to show them a photo of the cold spots on their radiators helps to make the argument more convincing.

    Both of these are great devices, but when you compare the images from the FLIR One against those from the Seek Thermal Compact I think it’s pretty obvious that the FLIR is the one to buy. And when you add in the supplied adaptors and other bits in the FLIR box it makes the case in favour of that device even more convincing.

    With the FLIR One it’s not just the MSX processing that makes for a great image – even if you switch that off the results look better than with the Seek Thermal Compact. The FLIR seems so much better at being able to detect relatively small temperature differences. There’s usually less noise in the FLIR images too.

    Finally, and this is a very personal point of view, if I look at the Twitter feeds for both companies, and their email marketing too, I can help noticing that Seek Thermal pushes its products as a device that’s of help to those hunting wild animals. This gives me yet another reason to happily endorse its competitor’s product, The FLIR One, as my smartphone thermal imaging camera of choice.

    (I will now stop hijacking @Tempted's thread!)

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