Navitron Renewable Energy and Sustainability Forum

HEAT PUMPS & Geothermal Energy => Heat Pumps => Topic started by: StBarnabas on November 29, 2010, 10:32:24 AM



Title: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 10:32:24 AM

As displayed on my greening of StB thread I have recently installed a 1000 Litre thermal store. I have about 50 square metres of floor fed by 4 ground loops and two oversize radiators. Sadly the system was installed by a plumber more used to traditional Central Heating and I have never been convinced that it was ever commissioned correctly. The flow rate through the UFH loops has never been very good but it is now almost non existent. It is currently 14.6 C in the kitchen and I am getting complaints! I have disconnected the zine controllers and opened the valves to the UFH loops wide open but with no success. The radiators are working fine and there is plenty of heat in the store.

Any ideas? Lightfoot did mention that as I am now running at 0.5 bar rather than 1.5-2 bar I might have balancing problems.

Any help welcome!

Sean


Title: Re: GSHP UFH Circulation problem
Post by: Ted on November 29, 2010, 10:48:11 AM
Can you turn off all the rads (at least temporarily) to force the UFH as the only open circulation route?


Title: Re: GSHP UFH Circulation problem
Post by: Stuart on November 29, 2010, 10:58:43 AM
Had similar problem with my rads now that gas boiler is working.

Set CH pump to full and blasted each rad one at a time to clear any air. was working ok not great. Couldn't balance the system up.

Had a long Chat to Lightfoot, and decided to investigate the pump as i has wrote the wrong numbers down and thought it must be a dodgy weak model.
Turns out it was a good one, and luckily the TMV Had overnight packed up. reveling the problem. The filters were a bit sludged up, possibly debris settled in the boiler flow and return pipes and a drip of solder!

Left filters out, working like a good un now.


Title: Re: GSHP UFH Circulation problem
Post by: SteveH on November 29, 2010, 10:59:43 AM
 I suspect you have air problems...

 My DIY UFH install in Wales would show similar reduced flow every time I had needed to drain down for any work. it was well laid out, but the new water added would carry quite a lot of defused air in it & this would find just the wrong spot to settle.

 My solution was to selectively purge each individual UFH circuit with the pump on maximum speed... I could hear the air coming out...

 Always worked for me & worth a try....

 Steve...


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 12:31:37 PM

All thanks for replies
Ted I have tried turning off all the rads and it does not solve the problem. SteveH I am trying to flush the individual loops - getting all of 1 Litre per minute through one of them.


Have just spoken to Stuart and it was obvious that it would be best to post a few pictures.
I have 2 manifolds one in the garage serving the utility room and a larger one serving the kitchen


Kitchen Manifold

(http://farm5.static.flickr.com/4113/5217729976_087c01038f_b.jpg)

Garage Manifold

(http://farm6.static.flickr.com/5210/5217736784_c542c52ca3_z.jpg)

Pump

(http://farm6.static.flickr.com/5006/5217729642_feca2f31d4_z.jpg)


Title: Re: GSHP UFH Circulation problem
Post by: Ted on November 29, 2010, 12:46:32 PM
I'll try to ignore that wiring!  whistle

How do you know the flow rate?
Is there a pressure gauge fitted on the UFH part?
Does the pump sound like it's under strain at all? 
Can you feel any heat along any of the pipes? Where does it change from hot/warm to cold?

An overall rough schematic would probably be useful.


Title: Re: GSHP UFH Circulation problem
Post by: Stuart on November 29, 2010, 01:25:10 PM
Labeled it up for you Sean,

Bet the pipes on the hot side are hot, and the flow will be low or even cold. The Gauze filters will be gunged up.

undo the big nuts 1st and the valve body will slide out (make note of the hot and cold sides! ), then the smaller nuts can be unscrewed. Mine had 2 filters.

should have took a photo when i had it apart!

I'll assume the pump gate valves are fully open  ;D

Stu


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 02:36:11 PM
Ted
as Stu said the flow side is hot or at least wam. The return seems cold. I attach a very rough sketch - need to find how to run PLANIX on my APPLE as all my drawings are in MS only compatible format. Yes the pump electrics do not look well connected! (Not my wiring I hasten to add)
Stu
Many thanks. Will give it a go. I also assumed the pump gate valves were fully open but will check!

(http://farm6.static.flickr.com/5245/5217952004_d36825b354_z.jpg)


Title: Re: GSHP UFH Circulation problem
Post by: Ted on November 29, 2010, 04:23:07 PM
OK, those photos start to make some sense now.

When you say the flow is hot/warm - up to what point? Just to the manifold?


Title: Re: GSHP UFH Circulation problem
Post by: welshboy on November 29, 2010, 04:58:33 PM
It might be handy to label the pics of the manifold etc to show the feed/flow to the radiators which you say are ok.


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 06:29:15 PM
Here is some annotation on the utility Room manifold. Hope it makes sense

(http://farm6.static.flickr.com/5250/5218548106_f113cd8483_b.jpg)


Title: Re: GSHP UFH Circulation problem
Post by: welshboy on November 29, 2010, 06:37:14 PM
Thanks for the pics.
Ours is a similar set up. ufh downstairs and rads upstairs. I balanced the rad flow by just turning the shutoff valve enough to get a flow otherwise it was starving the ufh. -taking the lazy way of least resistance. Ted suggested closing the shutting off valve - did that have any effect ?


Title: Re: GSHP UFH Circulation problem
Post by: Ted on November 29, 2010, 06:59:37 PM
I'm assuming that the 3-way valve with the red cap includes some sort of safety valve, to allow the hot flow to go straight to the return, bypassing the UFH.

Is the pipe directly above that getting hot?
Have you checked the filters in there (what a poor design!) for blockages as Stuart suggested?
What controls the internal setting of that valve? Could it have been inadvertently adjusted incorrectly? (I'm not familiar with that particular design.)


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 08:02:01 PM
Ted
the red mixing valve mixes some of the return with the flow reducing the temperature as there are some radiators on the system.

Have spoken to Lightfoot and he is in general agreement with Stuart that it is likely to be a blockage or airlock in the UFH sections. Though he is not at all impressed with the layout of the system!
Sean


Title: Re: GSHP UFH Circulation problem
Post by: knighty on November 29, 2010, 08:33:50 PM
at the mixing valve is after the pump, will it not just allow the hot water to bypass the ufh circuit and go straight back down the return ?

how hot/warm is the return from the ufh ? (at the pipe just to the right/behind the mixer valve)



I think for a system like that to work, the pump should be between the mixer valve and the manifold.... so it sucks in water..... and some of the return water will re-circulate to keep the loop temperature down ?


Title: Re: GSHP UFH Circulation problem
Post by: Ted on November 29, 2010, 08:49:54 PM
According to Stuart's annotation there are 2 one-way valves there to control direction of flow. But presumably the pump is sucking at the coolest part of the return?


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 09:02:02 PM
Ted

they are mixing valves (or so my plumber said). I will need to check the pump again. Lightfoot also hoped the pump was on the return rather than the flow (and was horrified I think about how it has been set up). He is going to send me some diagram as to how it might be set up properly. Sadly the builder I was using who subcontracted the plumber went into liquidation during the build. It sort of worked for a while but I had nothing to do with the system design. Wish I knew more when it was being installed.

Sean



Title: Re: GSHP UFH Circulation problem
Post by: knighty on November 29, 2010, 09:23:14 PM
can you close the mixing valves ?  (as a test?)

10 says that makes the system work ;)


Title: Re: GSHP UFH Circulation problem
Post by: Stuart on November 29, 2010, 09:32:47 PM
Mine is installed so the pump sucks the blended water through the valve.

(http://i6.photobucket.com/albums/y228/antimosh/house%20pics/IMG_3801.jpg)

I'd assume it requires positive pressure on both inlets to opperate correctly, sure there will be a proper plumber along to tell us soom  ralph:


Title: Re: GSHP UFH Circulation problem
Post by: desperate on November 29, 2010, 09:38:48 PM
Hi Sean,

Here's a downright filthy thought, your thermal store provides water at the ideal temp for UFH, so ditch the mixing valve baloney, there not much point in having it in the system at all, I am assuming your kitchen rad is fed directly from the store .

We have an UFH circuit fed as a zone directly from the CH controlled by a stat and 2 port valve, been working fine for 8 years now.

At cactusville we dont mess around with all those mixer doohickeys   horror:


Desp


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 09:40:58 PM
can you close the mixing valves ?  (as a test?)

10 says that makes the system work ;)
Oh yes have tried this a few times. Does improve things slightly in that the first few square metres of floor gets slightly warmer.
You owe me a pint when you next come to Newcastle!
Sean


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 09:44:39 PM
Hi Sean,

Here's a downright filthy thought, your thermal store provides water at the ideal temp for UFH, so ditch the mixing valve baloney, there not much point in having it in the system at all, I am assuming your kitchen rad is fed directly from the store .

We have an UFH circuit fed as a zone directly from the CH controlled by a stat and 2 port valve, been working fine for 8 years now.

At cactusville we dont mess around with all those mixer doohickeys   horror:


Desp

Desp
could well do. I can switch them off, which I have tonight. It's such a shame that the weather is such as it is for the past week! I was hoping to tweak the system before the bad weather set in but no such look!

Sean


Title: Re: GSHP UFH Circulation problem
Post by: Stuart on November 29, 2010, 09:47:14 PM
Turning the valve on and off must of dislodged some gunge and that worked for me for a short while too, have you checked the filters yet?



Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on November 29, 2010, 09:48:49 PM
Mine is installed so the pump sucks the blended water through the valve.

(http://i6.photobucket.com/albums/y228/antimosh/house%20pics/IMG_3801.jpg)

I'd assume it requires positive pressure on both inlets to opperate correctly, sure there will be a proper plumber along to tell us soom  ralph:
Stu
Looks nice, looks better than my dogs dinner!  I wish I contacted  lightfoot two years ago...


Title: Re: GSHP UFH Circulation problem
Post by: Philip R on November 29, 2010, 09:54:05 PM
Just noted Stuart's comment on the pump sucking through the mixing valve. There may lie a potential problem.

Suction of the pipework under negative pressure may suck in air through spindle packing glands and compression fittings. ( I witnessed this on a water cooling system with 4 bar positive head with a good system flow in my former workplace). High fluid velocities & turbulent flow regimes can produce localised vacuums, hence drawing in air as microbubbles.
Therefore try to locate the pump suction at the neutral point of system, i.e. where the head tank make up (if fitted) or expansion device.


Title: Re: GSHP UFH Circulation problem
Post by: chickensoup on November 29, 2010, 09:57:12 PM
Hello Sean,
               Can i suggest, while you've got things drained down, that you replace those manual air-vents on the manifold with 2 x auto air vents. They're a gods end on UFH manifolds.

     chicken


Title: Re: GSHP UFH Circulation problem
Post by: welshboy on November 29, 2010, 10:04:06 PM
Stb
You said you had turned the rads off but was it at the rad or the shutoff valve ?
If at the rad the lazy route may still be on


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on December 04, 2010, 10:21:42 AM
Sorry all
day job got in the way!    Here is a picture of one of the filters. I think that Stu was right! Filters now cleaned. System now back up and running looking good!

(http://farm6.static.flickr.com/5007/5231204392_fec26cd994_z.jpg)


Title: Re: GSHP UFH Circulation problem
Post by: Philip R on December 12, 2010, 12:35:16 AM
Hi StB,

That brown stuff in the filter looks a bit suspicious. It could be microbial slime or an excess of plumbers jointing compound.

It would be wise to keep an eye on these filters as more of the slime could appear. Just hope it is not m/slime. (I have seen this in several steam turbine lube oil systems and in fuel oil (red diesel ) tanks.  sh*tfan:

PhilR


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on December 12, 2010, 09:46:03 AM
Dear StB, what is your 1000 litre store charged with? Its a box on your circuit diagram, but do you have another circuit there to a solar thermal panel?
CTE
It is currently only charged by the GSHP. Due to the topology of StBC the solar system is totally independent of the GSHP system. The reason for the store is so that I can charge it up overnight using E7 electricity. As StBC is such a thermally heavy building this strategy works quite well.
StB


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on December 12, 2010, 09:53:28 AM
Hi StB,

That brown stuff in the filter looks a bit suspicious. It could be microbial slime or an excess of plumbers jointing compound.

It would be wise to keep an eye on these filters as more of the slime could appear. Just hope it is not m/slime. (I have seen this in several steam turbine lube oil systems and in fuel oil (red diesel ) tanks.  sh*tfan:

PhilR
Phil
many thanks. Interestingly the return filter was as clean as a whistle so I do hope it is nor microbiological in origin. I have some  more inhibitor which I can add as necessary and I will indeed keep a close eye on it.
Sean


Title: Re: GSHP UFH Circulation problem
Post by: renewablegraduate on December 28, 2010, 07:12:09 PM

All thanks for replies
Ted I have tried turning off all the rads and it does not solve the problem. SteveH I am trying to flush the individual loops - getting all of 1 Litre per minute through one of them.


Have just spoken to Stuart and it was obvious that it would be best to post a few pictures.
I have 2 manifolds one in the garage serving the utility room and a larger one serving the kitchen


Kitchen Manifold

(http://farm5.static.flickr.com/4113/5217729976_087c01038f_b.jpg)

Garage Manifold

(http://farm6.static.flickr.com/5210/5217736784_c542c52ca3_z.jpg)

Pump

(http://farm6.static.flickr.com/5006/5217729642_feca2f31d4_z.jpg)


seriously that pipework and manifold work is really poor, come on guys have some pride in ones work


Title: Re: GSHP UFH Circulation problem
Post by: desperate on December 28, 2010, 07:19:47 PM
Hallo Renewable grad,

It might have been a bit more tactful to enquire who installed it, no? ;)

Desp


Title: Re: GSHP UFH Circulation problem
Post by: renewablegraduate on December 28, 2010, 07:23:48 PM
Hallo Renewable grad,

It might have been a bit more tactful to enquire who installed it, no? ;)

Desp

it does not matter who installed it, there is no excuse for hep fittings getting used with copper on show like that, renewable energy installations should be of the highest quality not DIY bodges :ballspin


Title: Re: GSHP UFH Circulation problem
Post by: Alan on December 28, 2010, 08:08:20 PM
Don't knock it   Hep fittings

7 drain downs / replace last week.

I picked up loads of work last week replacing hep fittings with proper pipe work :hysteria

Regards

Alan


Title: Re: GSHP UFH Circulation problem
Post by: EccentricAnomaly on December 28, 2010, 09:08:04 PM
...there is no excuse for hep fittings getting used with copper on show like that, ...

For my education, what's the problem with such a combination?


Title: Re: GSHP UFH Circulation problem
Post by: Alan on December 28, 2010, 10:34:16 PM
I have used 7 layered Phex pipe with the correct inserts and fittings on under floor heating systems.
Absolutely wonderful stuff. Never had a problem.

Last week and about this time last year as soon as it got a bit cold. Hep fittings popped off. Solder and brass compression fittings survived.

Here if at all possible pipe work is soldered. Brass is used on very rare occasions.

Regards

Alan


Title: Re: GSHP UFH Circulation problem
Post by: renewablegraduate on December 28, 2010, 10:34:27 PM
...there is no excuse for hep fittings getting used with copper on show like that, ...

For my education, what's the problem with such a combination?

ive been a heating engineer for 15 years anyone worth there salt in the industry knows that hep is to be used with hep fittings in unseen locations, copper on show always, why would you spend the money on an expensive system and give a finish like the one in the picture, whoever believes that the standard of work is acceptable shouldnt be involved in anything to do with the installation of systems :-*


Title: Re: GSHP UFH Circulation problem
Post by: desperate on December 28, 2010, 11:31:14 PM
In principle there's nothing  technically wrong mixing hep and copper, but it does make clipping tricky, and looks a bit naff, but I've seen many more dodgy comp fittings than Hep.


Desp


Title: Re: GSHP UFH Circulation problem
Post by: EccentricAnomaly on December 29, 2010, 01:01:52 AM
ive been a heating engineer for 15 years anyone worth there salt in the industry knows that hep is to be used with hep fittings in unseen locations, ...

Remarkably, not everybody on this forum is in the industry but many might want to do some plumbing and would like to pick up useful hints and avoid pitfalls.  You could, like Desperate, have just said that it looks naff without bothering to tell us how long you've been whatever.  Sentences run together without appropriate punctuation or capital letters look naff, too, by the way.

Quote from: desperate
...but it does make clipping tricky...

Am I right in assuming the fittings are large so the pipe finishes up too far from the wall for standard clips?

Quote from: Alan
Last week and about this time last year as soon as it got a bit cold. Hep fittings popped off.

Is this due to differential contraction, do you think?


Title: Re: GSHP UFH Circulation problem
Post by: marshman on December 29, 2010, 11:16:11 AM
Not wishing to get into the "it doesn't look pretty debate" mainly because some of what I have done in the past wouldn't bear close inspection ::) I would however like to comment on Copper pipe and plastic pushfit fittings.

I have had underfloor heating for 25 years. Never had a leak from any fittings they are all "pukka" brass insert, olive and brass compression fitting - and they all come apart easily when I have modified the system. I have at various times used push fit onto copper - speedfit - hep etc. I would say without exception after a period of time the ones on the hot side have "crept" and started to leak. Yes they are quick and easy but I have reservations about their long term (25 year plus) reliability on hot water systems. I beleive the problem occurs because of the repeated contraction and expansion of the pipework as it heats up and cools down.

I would also like to make the comment that in my opinion the circulation pump for the UFH system should be pumping round the loops all the time and the mixer valve should be the other side. This keeps the loops at a constant temperature with the mixer/bypass valve modulating the supply of fresh hot water to keep the temperature correct. I suspect you really need two pumps. One for the UFH and another for the rads. I know their are differing views on this but as I say I have had underfloor heating for 25 years and have studied how it operates and what works best for maximum comfort for minimum energy!

Just my 2p worth :)

Roger



Title: Re: GSHP UFH Circulation problem
Post by: renewablegraduate on December 29, 2010, 12:08:36 PM
ive been a heating engineer for 15 years anyone worth there salt in the industry knows that hep is to be used with hep fittings in unseen locations, ...

Remarkably, not everybody on this forum is in the industry but many might want to do some plumbing and would like to pick up useful hints and avoid pitfalls.  You could, like Desperate, have just said that it looks naff without bothering to tell us how long you've been whatever.  Sentences run together without appropriate punctuation or capital letters look naff, too, by the way.

How long I have been whatever ?. This clearly shows the fact that anyone I have come across in the industry would not accept that standard of work. That was the only point I was trying to make. As for punctuation, don't make me laugh this is a renewable forum not a writing club. I have written five books on engineering so settle down would you.  whistle


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on December 29, 2010, 02:48:20 PM
For the record this was installed by a "professional plumber". It is not a DIY bodge, (just a bodge of a different sort) but to be honest I would have designed the system very differently if I had done it myself, as I tend to be a perfectionist. The bit that was installed by Desp looks far nicer, all brass and copper with very neat joints. I'm more worried about the overall design of the system and when I install the UFH system in the chancel next year this will be a good opportunity to redesign the system.
Sean


Title: Re: GSHP UFH Circulation problem
Post by: renewablegraduate on December 29, 2010, 03:08:54 PM
Im glad to hear it Sean, I can see how you may be worried about the overall efficiency and design of the system. Maybe tidy up the initial pipe work when doing the renovations to the property?. Wouldnt cost much to tidy up them manifolds.


Title: Re: GSHP UFH Circulation problem
Post by: desperate on December 29, 2010, 07:38:08 PM
Personally when I install an airing cupboard say, the last thing I do is to run copper out of sight and then switch to hep, all that does is to make the hep fittings inaccessible, why not install all the manifolds, valves, pumps etc onto copper and then switch to hep just before it goes below floor level or above ceiling etc, any problems are easily found then. Plumbing should be designed first and foremost for utility and maintenance rather than looks.

Mr EA as you say standard clips don't have enough clearance to the wall for hep fittings and a manifold built from push fit is a very wobbly affair that needs a lot more clips than a nice rigid copper assembly. Also I find it a bit of a fight to insulate the fittings satisfactorily.

For what it is worth we use hep by the mile and clipped up properly it hasn't given us grief..............yet help:


all the best

Desperate


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on December 29, 2010, 09:18:57 PM
Desp,
agreed but remember:

http://www.navitron.org.uk/forum/index.php/topic,2162.0.html (http://www.navitron.org.uk/forum/index.php/topic,2162.0.html)

plastic pipe is still a big worry...
StB



Title: Re: GSHP UFH Circulation problem
Post by: Stuart on December 29, 2010, 10:37:02 PM
if your doing another BBQ i'll sharp replace those HEP with a bit of solder ring for you  ;D


Title: Re: GSHP UFH Circulation problem
Post by: Antman on December 30, 2010, 10:19:59 AM
Who the pling wired the Grundfos pump Sean  whistle

Antman


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on December 30, 2010, 12:20:23 PM
Antman
Not me! Done by my "professional" plumber  whistle.......


Title: Re: GSHP UFH Circulation problem
Post by: dhaslam on December 30, 2010, 12:26:11 PM
Isn't copper pipe now  a bit of a dinosaur?       Almost 50% of the houses in Ireland have had leaks in their pipework this winter, some may be in old lead piping but the  majority is in copper pipe.   I suppose plastic pipe will burst as well  but not as easily.


Title: Re: GSHP UFH Circulation problem
Post by: renewablegraduate on December 30, 2010, 04:45:24 PM
It is all about mapress now , get a REMS gun and use copper or carbon.Joints done in an instant and never any problems.  8)


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on December 30, 2010, 11:46:16 PM
if your doing another BBQ i'll sharp replace those HEP with a bit of solder ring for you  ;D
Stu
 will have a BBQ though not just yet! Will try to organise a renewable weekend this year - have been thinking abut a small renewable workshop for a while.
Sean


Title: Re: GSHP UFH Circulation problem
Post by: Stuart on December 31, 2010, 09:39:52 AM
Think we should borrow that Proven from the university?


Title: Re: GSHP UFH Circulation problem
Post by: StBarnabas on December 31, 2010, 10:31:04 AM
Good plan. Will work on it
Sean