Existing problems with central heating system (new build)

[deefadog]

Hi all, hope this is the place i can get some good partial advice (Actually going to start a plumbing course in a moths time, so this will eb learning curve as well).

Basically, I live in a new build 3 story town house, been here for just over 2 years. During this time we have had lots of problems and typically as the 2 years cover has finished i have another (losing pressure). Also British Gas will not cover us, as they the system is to complicated for them and not worth their while

I basically want to check that everything has been installed corectly as the last problem we had, they (barratts contractor) had plumbed in 2 pipes the wrong way around (technical names i forget) But every time the hot water came on water was released through PRV.

I think the best way to show you will be to created a detailed diagram (I'll do this over the next few days, if this will help???

So hope you guyz can help me out and sorry to ramble on LoL

 

[sonray ltd]

think you best draw a diagram.
what is the boiler or type of system you have ?

 

[deefadog]

Thanks mate, I'll try to describe the system the best i can (The diagram will help a lot i feel) - the boiler is an ideal ICOS and it is a sealed system (i think). It has 2 expansion tanks next too the cylinder on the top floor. The original heating system was split into 2 zones, Zone 1; Lower floor and middle floor consisting of 10 rads. And Zone 2 (top floor) consisting of 9 rads.

We had a lot of problems with the fixed thermostats and the house did not warm up as we wanted, so now all the rads have the wireless TRV's - Honeywell CM zone system - HONEYWELL CM ZONE SYSTEM.

The problem we have now is that the presure gauge by the tank is losing pressure always at 0, i can top it up to around the 1 bar (as we have been told) but once the heating has been off, it's at 0 again. Now this would suggest a leak, but i have maticulously checked all the rads, walls, pulled carpets up all over the house and i can not find any leak! As it's not coming out of the overflow as it did before when the pipes were install incorrectlly.

 

[sonray ltd]

theirs a leak somewhere in the system. you could always try some leak sealer.

 

[deefadog]

Hi thanks for the reply, you mean this product? - CENTRAL HEATING INTERNAL LEAK SEALER

So you mean the system is leaking externally? - I would estimate that from 1 bar to 0 bar when refilling (though the loop) that at least a pint is escaping, surely i would notice this.

Or could in be another wrongly plumbed problem and it's leaking into the tank??

When the heating is on, the pressure goes up to around 2.9 bar which i have been told is correct and i don't seem to be loosing heat in any rads, what i don't understand (probably because i am not a plumber) is that if a normal working system set at 1 bar cold and goes to 3 bar when fully on, then if i lose that initial 1 bar pressure then on full load it would only go to 2 bar? does that make any sense LoL - or does it not work that logically?

 

[Mike Jackson]

The pressure rising from 1 bar to 2.9 bar when the heating is on is not correct. It would indicate some sort of problem with the pressure vessel, possible undersized or faulty.

The guarantee may have run out but if the system was incorrectly installed in the first place I would still expect them to put it right.

Ideally you need a reputable heating engineer in to do an inspection and write a report for you.

Mike

 

[deefadog]

i Mike, thanks for the comments, not doubting you in any way but we actually had the ideal expert out (he was the one that found out that the pipes were installed incorrectly, causing the PRV to activate when the hot water was on) He talked me through the system and said that 2.9 was normal, as it's within the black (dark green i think) segment on gauge, he said if it goes past this then the PRV out release the excess pressure. i actually have 2 of the pressure vessels.

Getting a reputable heating engineer is my next step, but i just wanted to let a wider audience of people in the trade express their views before i did this

I'll get the diagram done by the end of the week and add some pics also.

Out of interest from a cold system what is the behaviour of the gauge? should the hotwater have any effect on this gauge at all?

Thanks

 

[mcmoby69]

first thing i would do is get onto barratts and tell them to get their fingers out and put it right. tell them you are going round all the neighbours and getting a full list of faults together. then suggest a trip to watchdog/ rogue traders and trading standardsmay be an option . also a phone call to the nhbc. infact anyone who could put some bad publicity their way! for the price of a new house i would expect the heating system to last a shade longer than two years! i would also suggest a phone call to corgi. just be aware that plumbers working on new build are usually on bonus so corners are cut! no idea what your rights are regarding a house purchase but you could look them up (consumer rights act 1974). good luck!

almost forgot! the ideal expert who said the presuure at 2.9 was ok
was
a not ideal and
b not an expert!

 

[red man walking]

make sure the plate heat exchanger in boiler is not split inside as this may cause water to discharge through condensate so you wouldn't notice any leaks. I think this is correct, some plumber told me he had this problem on a baxi duo-tec. Took him ages to find it.

 

[deefadog]

Thanks i'll check the plate.

[DLMURL="http://www.ukplumbersforums.co.uk/members/mcmoby69.html"]mcmoby69[/DLMURL] - Thanks, good job i came on here to check first, god, makes it hard to believe any trades men, or maybe as you say, contractor trades men - they are on peanuts and rely on bonus, so cut corners.

So out of interest (and for me to put an argument across to barratts) from a cold system what is the behavior of the gauge? should the hotwater have any effect on this gauge at all?

ironically with all this going on, the heating is spot on and so is the hot water Lol. If i was not a fussy git and did not keep an eye on it, i may never have noticed this until something big happened!

 

[Mike Jackson]

I would expect the pressure in a system to rise by 1/4 to 1/2 bar at the most when it heats up. Certainly not 1.9 bar.

Have a look at [DLMURL="http://www.rwc.co.uk/content.aspx?page=ABOUT_EXPVESS"]Reliance Water Controls[/DLMURL] for info on sizing expansion vessels. It's a bit over the top but it gives you an idea what sort of size the vessel should be.

MIke

 

[deefadog]

Thanks Mike, in work at the moment, but looking at that, i'd say my problem is that my expansion vessel is way to small. I'll get the correct sizes tonight, but as a guide - the Cylinder is the height of me, around 5' 10" (it's a biggie) and expansion tanks are only around 1' 6" in height.

To try and narrow down where this leak is, on the weekend (can't do it in the evenings because of the kids) I'll let the system cool down, top up the system to 1 bar, then just activate zone 1 of the house for half an hour. let it cool down and see if anything has been lost and repeat with zone 2.

Also a few questions (again) sorry -

1) any idea (roughly) on how much a report would be by a reputable plumber?

2) As the system pressure is too high when the heating is opn, what can this cause? too much stress on joints and radiators?

Many thanks

 

[mcmoby69]

without the benefit of a drawing, it sounds like the expansion vessel for the central heating circuit is too small( you said there were two? the other one may be for the hot water cylinder?) difficult to tell without being there. 10 rads on 1 circ and 9 on another, a normal combi usually copes with a 10 rad system you have almost double! bearing in mind this was a new build only two years ago i think you should keep your money in your pocket and give barrats some serious 'victor meldrew' treatment. get hold of that bald london bloke who knocks about with melinda messenger. as a bonus you could end up with her on yoour doorstep! they catch upwith dodgy builders etc!

 

[deefadog]

Hi mate, i'll get that diagram up on the weekend & photo's. Just to point out it's not combi boiler. and when i said the pressure raised up to 2.9, i was wrong, it's 2.1 - still more than has been recomenned on here, but thought i put that right

God, i love melinder

 

[mcmoby69]

sorry about the 'combi' bit, slightly obvious if you have got a 5 foot water cylinder in a cupboard! (had a bad day and a couple of shandies when i posted.
it is a system boiler, still needs a correctly sized expansion vessel with it!

 

[deefadog]

No worries

I have tried to upload pics today, but i am having trouble (macs and network connections).

But here is some info:

Cylinder - Range tribune HE 250L indirect

expansion vessel - Varem - 2.5 pressure bar / max working pressure 6.0 bar. There is another expansion vessel but could not see any stickers on it, it was about the same size but the bottom of it was different (can see in pics when i upload them)

Incidentally, today, i had the heating off and filled the up the system to 1 bar, after 2 hours it had fallen to half a bar where it stayed. I then noticed that the Hot Water came on from the timer and this raised the gauge by 1 bar to 2 bars. Is the Hot water able to effect the gauge like that? I thought they were 2 separate things?

 

[John Flower]

Range Tribune ! If i am correct is not an unvented cylinder but a thermal store ! That would definately make the system pressure vessel undersized. Due to the amount of primary water in the store.

 

[deefadog]

Thanks for the input! - I still busy with the diagram, difficult with young babies, but should finish it this week i hope.

 

[plumbnuts]

Hi
In answer to your question about the behaviour of the pressure guage :-
When the boiler/water content is stone cold, the reading should be just above 1 bar. When the boiler is on, the guage should steadily rise. This is due to the expansion of the system as the water gets hot. The expansion vessel accomodates this expansion and the guage shouldn't realy get above 2 bars. If it does, there is a problem as mentioned with your expansion vessel being undersized or incorrectly charged. If the guage reads 3 bars or above, the pressre relief valve will operate and eject water from the system through a designated pipe. This will cause a pressure drop and will damage the pressure relief valve causing it to contstantly leak. Hope this helps?
Steve

 

[deefadog]

Hi, thanks (still have not had time to finish the diagram, been busy in work, but will attempt to finish this soon).

Thanks for the info. Would the gauge rise if just the hot water is on, or should the hotwater not effect the gauge at all?

Also, i know the Pressure release valves are not releasing any water this time, as the pipe the water comes out of is outside the front door and you can see from the tarmac if any water has come through. (I used to have this happen everytime the hotwater came on as the pipes were the wrong way around to the expansion vessels, last year)

 

[plumbnuts]

The guage will rise when the hot water is on but as stated it shoud not really get above 2 bars and even then only when the sysyem is very hot.
Steve

 

[deefadog]

Thanks Steve. It goes to 2 bar when HW comes on and 2.1 when the Heating comes on.

Actully as i seem to be losing pressure, it goes to 2 bar HW & 2.1 Heating even if the gauge is at 0 bar, is this correct? i would assume if it was doen by 1 bar to 0 bar then it would only go to 1 bar when the HW comes on? or is this not how it works?

Cheers

 

[plumbnuts]

No, it wouldn't normally work like that. Dependant on your system, some boilers have a safety cut out if the pressure drops below 0.5 bar. If there are no singns of water as you say, my other thought apart from those already mentioned is that maybe your pressure guage is faulty. It could be the guage dropping to zero. Do you have any other means of testing the pressure in the system?
Steve

 

[deefadog]

Thanks, well at least you have put 2 uncertainty's to rest - yes it could be the gauge. it did cross my mind, but i refilled it at least 4 times now, so i woudl assume if the system was ok, then it would be overfilled and the PRV would do it's job? and i could see this?

I have no other way of testing the pressure, is there something i could buy?

 

[plumbnuts]

The other way in which the system can lose water unnoticed is if the heat exchanger is leaking. The water from this will just run away down the condensate pipe without your knowledge. You could test this by doing the following-
Turn off boiler
Presure system to just under 3 bars
Turn off isolaters on flow and return under boiler
See if the pressure drops. If it does the water is being lost within the boiler.
Open valves again and observe guage, if it rises the leak is in the boiler, if it falls, the leak is in the system.
Steve

 

[deefadog]

Top stuff, thanks steve! when you mean turn boiler off, can i just set the system to frost setting i.e 5 degrees C. as i don't fancy turning it off at the wallin case i can't get it started again, especially as it's gone cold again.

Thanks again!!! really appreciated

 

[plumbnuts]

Because by isolating the boiler you have in effect reduced the water content that the guage is measiring to just a few litres. If the leak is in the heat exchanger the guage will drop quickly, so your boiler should not need to be off for long

 

[deefadog]

Aha i see thanks! Will give it a go!

 

[plumbnuts]

let me know how you get on

 

[deefadog]

Will do! Pity you not in south wales, i'd commission you to sort it out

 

[deefadog]

Hi, have not had a chance yet, been away with work, But will get on with this, this weekend.

Also i'll get that diagram sorted also.

 

[jskdog]

I have exactly the same problem as soon as i switch the hot water on the prv lets water out the top of the tank, i have noticed that on one of the expansion tanks (the one with the gauge)a tap to it is switched off, does this need to be on?

 

[deefadog]

Hi, no the tap i assume is the filling loop to top the system up. This is the original problem i had and has since been corrected, some pipes were installed the wrong way. You could also have a faulty PRV - I think they are set to release (open) at 3 bar pressure - check the gauge and see if it goes up passed 3. You'll prob have to let the heating and hot water be off for 4 hours and refill with the loop to get the gauge back to 1 bar (or what ever it should be).

 

[jskdog]

Just tried attaching some photos not sure if it worked?

 

[deefadog]

Nope can't see anything?