New expansion vessel needed?

[Phill Peck]

I don't know the size of vessel in Worcester but often around 6-8 litre so as U say around 100 litre max.

TBH I rarely attempt to calculate the volume, if it's a 4bed plus i stick and extra 12 litre vessel in airing cupboard.
Takes strain of expansion off boiler vessel and system.
As Tony points out external vessels are cheap

 

[Aquaheat]

I don't know the size of vessel in Worcester but often around 6-8 litre so as I say around 100 litre max.

TBH I rarely attempt to calculate the volume, if it's a 4bed plus i stick and extra 12 litre vessel in airing cupboard.
Takes strain of expansion off boiler vessel and system.
As Tony points out external vessels are cheap

I agree Phil but it's not a common day practice to come across a 4 bed plus. Usual is a 2/3 bed semi which I well within the 100 litre mark.

As I mentioned in my previous post if it is any larger then this should be brought up with the homeowner and also why it wasn't done on the original design.

Extensions being a major factor. A homeowner has a 3 bed where the boiler works fine, they then extend and add another 2 rooms and a bathroom and UFH and wonder why the heating goes crap.

Jon

 

[DP]

I always explain the options ( and costs ) to the customer.

So do I. Am sure so does almost every heating engineer in the country

 

[Phill Peck]

So do I. Am sure so does almost every heating engineer in the country

Are u sure u do that I heard you were number 124 so probably a cowboy

 

[Aquaheat]

Are u sure u do that I heard you were number 124 so probably a cowboy

I'm 125 Phil what does that make me?!

Anyway play nice or your 69 status will be taken away!

Jon

 

[Phill Peck]

I'm 125 Phil what does that make me?!

Anyway play nice or your 69 status will be taken away!

Jon

Come on Jon don't be so hard on yourself.

 

[Aquaheat]

My hard on status always has to be dealt with by myself!

I'm off out to look for a lady in a saree and a place that will let me bring my own wine!

Jon

 

[omega015]

So I closed most of the radiators I could get to (couple are inaccessible) opened the drain off and let whatever pressure / water in the system out. When pumping the expansion vessel back up it felt like I could keep pumping forever until eventually it started to hold some pressure which dropped off after a while. I thought maybe a slow puncture inside but I'm thinking more likely it could of just been the air leaking back out through the pump somewhere. Gave it between 0.75-1b of air in the vessel and it seemed to hold so quickly disconnected the pump and refilled the system, bled the air out, pressurized system to 1bar and ran the system on the coldest/frost setting and again checked all rads for trapped air and ensured system was still at 1 bar.

I put the heating setting back on highest temp and ran everything for a while and the pressure seemed to hold at no more than 2bar. So fingers crossed it just needed some air back in the expv. I have delayed the engineer coming out until the system has been running for a few days - a week, to see if I notice any change to the pressure. Noticed a miniscule amount of water had escaped from the PRV into the bag I put over it (couple of drops overnight). I understand that once these things have been activated its common for them to continue to drip/leak due to crap that can be in the system, I shall see how much leaks from there over the coming days also.

From the previous convo about adding external expansion vs replacing the "internal" one. I agree, that it definitely should be the customers decision AFTER they have been fully advised the cost/work involved and any pros/cons of both options.

 

[Agile]

pressurized system to 1bar and ran the system on the coldest/frost setting and again checked all rads for trapped air and ensured system was still at 1 bar.

I put the heating setting back on highest temp and ran everything for a while and the pressure seemed to hold at no more than 2bar. So fingers crossed it just needed some air back in the expv. I have delayed the engineer coming out until the system has been running for a few days - a week, to see if I notice any change to the pressure.

If the pressure increases fro 1.0 bar to 2.0 bar when hot then certainly it is not operating correctly.

But you don't say if you let all the water out of the air side as advised. That has to be done BEFORE depressurizing the system!

In a properly sized system the increase should only be about 0.3 bar.

Tony

 

[PullerGas]

It's always advisable to replace the schraders valve too. I just bought 100 for £1.50 on Fleebay.

With the system/boiler drained, pump up the EV, fill the system again & remove the schraders valve. If water pizzes out the valve for a good 5-10 minutes, then the diaphragm is Frier Tucked.

 

[Agile]

I also have a stock of spare valve inserts.

But rarely find any leaking.

Although don't know why, sometimes they will not let the air in!

 

[omega015]

I got as much water out as would come out of the valve, it was hard to contain the water so some kitchen roll was needed but it didn't seem like there was very much water in the air side (maybe a couple of shots worth at most). I'll see what the pressure is like when I get home and then fire up the system and see what the pressure difference is this time.

Can the valves be changed in place or do you need to open up/take off the ev in order to change it? its a bit of a tight fit to even get to the valve so probably not likely changeable in place anyway though.

 

[Agile]

Are you quite sure that you kept the system unpressurised while pumping up the air? It is part of the procedure for checking the diaphragm is not leaking that it will retain air pressure when the system water pressure is zero. Apart from the need to ensure that it contains the maximum volume of air.

The PRV can drip for several days after being manually opened.

Unless the schrader valve is leaking air there is no need to change it.

Most RGIs would apply some leak detection fluid to the valve after pumping it up to check it.

Tony

 

[PullerGas]

Are you quite sure that you kept the system unpressurised while pumping up the air? It is part of the procedure for checking the diaphragm is not leaking that it will retain air pressure when the system water pressure is zero. Apart from the need to ensure that it contains the maximum volume of air.

The PRV can drip for several days after being manually opened.

Unless the schrader valve is leaking air there is no need to change it.

Most RGIs would apply some leak detection fluid to the valve after pumping it up to check it.

Tony

Why would anyone use the PRV to drain the boiler/system & as for it dripping for several days???!! Jesus Tony, you been on the Meths again??!!

Most RGIs I know change the schraders valve, it costs pennies & a five minute job!!

 

[omega015]

Absolutely sure, as some more water was forced out the drain off as I was pumping it up. I even did it all twice as I forgot to open one side of the radiator first time and thought probably both flow and return sides need to be open at the radiator. I double checked that the drain off was open while I was adding air to the ev and noticed it started holding pressure. I'll check the pressure this evening and see if any more water comes out of the ev if the pressure has changed.

The PRV was not manually opened it was opened because the system went over pressure at some point which is what caught my eye the other morning, which lead me to the ev having no/little air (but a little water) in it.