Two new open vent boilers, problems ever since.

[Neel94]

Hi all,

So I re done my house 2/3 years ago and had all my radiators taken out on the lower floor, changed to wet underfloor instead. 2 zones. 2 manifolds. As I was doing quite a bit, I’d decided to exchange the two 15 year old boilers with a pair of new ones. Vitodens 100w 35kw open vent.

Ever since I’ve had these new boilers put in, the pressure to all the bathrooms seems to have gone to crap, I have 5 shower rooms and if more than 2 are being used, other showers struggle to get a decent bit of pressure out, and sometimes the shower on the second floor completely stops extracting water.

Not sure what the plumber done, I increased the pressure in the airing cupboard and it helped a little, but still sometimes the shower upstairs (2nd floor) completely loses water and ever since I’ve increased the pressure I can hear the pipes in my house vibrating when ever someone uses the water from any valve, e.g. toilet, sink… is it okay to increase the pressure in the airing cupboard to about 3/4? They guy who installed the whole plumbing system when house was built in 2001 left some notes that the pressure should be set between 1 & 1.5 bar and not to exceed. I recently put pressure back down to 1.5 due to excess vibration from pipes as I’m worried something might burst. (Now it takes about 45 seconds for water to come out the shower on 2nd floor, and sinks literally have no pressure). Literally never had these issues before i had the new boilers put in.

Also, seems like the towel radiator in the bathroom (2nd floor) is only getting hot 3/4’s. Thought it was air, so bled the rad, hissed for a bit, but then no water is coming out?! Also same situation with the rads in the room where the bathroom is. Is this also connected to a potential pressure issue?

Look forward to some of your advice.

 

[king of pipes]

Post some pictures your installation, do you have a storage of hot and cold water ? I'm a little confused the title says open vent boilers then you quote you can up the pressure ?? we will need more information to advise you correctly. Regards Kop

 

[snowhead]

As KOP above it needs a lot more info and photos.

Did the house have 5 shower(s) / rooms before the new boilers were fitted and if so did they all work O.K?

Are the new boilers open vent, not a sealed system and no expansion vessel?
Are the new boilers Heat only, ie. NOT a combi?

Is there a hot water cylinder(s) and if so is it Unvented, i.e no header tank in loft and a pressure regulating / relief valve set attatched to it, is this what you are adjusting?
And was this replaced in the works done?

Is the cold water from a storage tank in the loft or direct from mains cold / balanced port on the pressure regulating set, was this changed in the boiler replacement work?

 

[Neel94]

There is a pressure screw with psi and bar written on it in airing cupboard, I turned it down last night and vibrations stopped but no hot water to showers or sinks.

5 showers are all the same, except bathroom on 2nd floor was re done with a towel rad replacing traditional rad.

They’re open vent, it says it on the boiler and there’s no pressure gauge on the boiler. There is no tank in loft, it’s mains fed. We have a massive hot water tank in airing cupboard.

The boilers do both heating and hot water. It says on the boiler regular boiler?

The pressure dial which I screw has been there since house was built. You can see in picture it’s black.

Do this grundfos pumps have anything to do with it?

I live in quite a large house would I have any circulation pumps? I asked my plumber and he said he doesn’t believe so, it’s all mains fed.

Also what is this heat pump with timer on it? Is that a pump to increase pressure? I’ve had it set to off but I turned it on this morning and no difference. Could this be the problem

Sorry I’m a noob to this all.

 

[gmartine]

It's a regular OV boiler but as you don't have as small feed tank in the loft it's sealed so there is nothing about this system that is open vented despite the label on the boiler.

Your hot water is supplied by the unvented cylinder but we can see from the pressure guage on the twin pump there is no pressure whatsoever which is why you aren't getting any hot water. You need to open whatever screw you closed and repressurise the system if you want to shower.

Looks like the cylinder might need a service or a check over cos the tundish is a mess and it's leaking or has leaked some rusty water. Whats the small circulator with that manual timer secondary circulation? (open question)

 

[Neel94]

Based on this label attached by original installers, it says heat pump…. Everything is labelled. Is this to get instant hot water? I turned it on and it made no difference to pressure.

What I turned for pressure was the black nozzle you can see in first pic.

Also look at this first pic, it says pressure should be set to 1-1.5 bar. Is that for the black nozzle or for the grundfos pumps? There’s two needles on the gauge for the pump. The black one is at 1, the red needle is at 0 all the time. Does that mean anything ?

 

[king of pipes]

You have a sealed system which is has no pressure in it which won't help, the question is why ? . If You've messed with that pressure reducing valve the one with the black handle then put it back to its original setting , the cylinder looks like it could do with some work you will need a service call from a registered engineer who understands these type of systems , kop

 

[gmartine]

Edit...twin pump is obviously for central heating not hot water as I stated above.

 

[Ben-gee]

You got your colours muddled. The black needle is at zero - this should be about 1 bar when system is cold.
The red needle is in fact not a needle that is connected to anything, it is merely set as a guide to where the black one should be.

As above you really need a G3 registered plumber to look at the hot cylinder, and the heating system.