System noisy and sucking in air after new pump install -Help please.

[PSH]

A few weeks ago, a heating engineer replaced our old Myson pump which was not circulating the water fast enough, which was causing all the radiators to run cool along the bottom. The old Myson pump which was blue and had been in the house for 25 years , and it’s identification label had come off. Along with a 2 position electric switch, it also had a metal lever, which when new could be turned to either “Min “or “Max”, but was jammed on the “Min” setting. So he fitted a brand new Grundfos UPS 15-50-130 Selectric pump, and now all the radiators are hot all over. The problem is ,we can now hear the sound of water cursing through each radiator, and every half hour or so, air can be heard gushing into some of the radiators. The new pump is on it’s slowest setting and I have bled all the radiators each night since it was fitted, but the sound persists and air is still in the system . I rang the engineer and he said that as the new pump is working properly , air is now being sucked into the system, probably through the valves on the radiators, (not the TRV’s) and asked me to tighten up the nut on each valve, in case the gland had got slack. If this did not work, he suspected the dumball valve might be faulty and may need replacing . According to Grundfos Technical department , he has fitted the correct pump. My question is this , is the new pump causing cavitation ,ie, aerating the water ,inducing air bubbles, which makes me think the new pump is too powerful, or is the engineer correct in his assumption about air leaking in through the valves or the dumball valve causing this new issue. Could you guys give me your thoughts on what might be happening please.

 

[lame plumber]

could be the pump isnt in the correct position and is sucking air into the system/ pumping over via the f & e tank. get in a diferent plumber to check it out, if you believe that air can be sucked in to the rad valves, surely when the heatings off youd see water pouring out said valves! not sure what a dumball valve is, its a new technical term to me!! first thing tho is to bleed air out of the system and see if that is the issue or whether air is being introduced due to poor system design. google pump neutral point for more info

 

[dieseldong]

Hi If it wasnt doing it before new pump was fitted, chances are plumber fitted it wrong way round and is now dragging in air as it is flowing in wrong direction
I think the bumball valve is the same as a foo foo valve

 

[Billy Bob Bob]

dragging air in via the rad valves?:smilielol5::smilielol5::smilielol5::smilielol5::smilielol5::smilielol5::smilielol5::smilielol5::smilielol5:sorry but thats the lamest excuse i have ever heard

 

[vern]

Just for ref a "dumball" valve is a spring loaded anti gravity valve....

 

[PSH]

Thanks to all who have replied to my thread.
1. What do you mean by an F and E tank and pumping over please . Do you mean air is being sucked back in through the over flow pipe which feeds any excess water from system in to top of header tank ?
2. I googled “neutral point” and found another similar thread ,which suggested air was being sucked in via the header tank, how can this be possible if water level was covering the water feed pipe, unless they mean what i have described above.
3. .I said to the plumber, if air can be sucked in, then surely there would be water leaking from valve, but he said not if it was a minute air leak, as air is thinner than water ,any way ,not convinced but worth a try as it is a simple thing I can do myself. He said that if tightening up the valve nut failed, switch pump off ,remove nut and apply ptfe tape around thread, but i am worried water will gush out if i try this, will it guys ?
4. He drained the whole system down when he swopped pump, so how many times would you expect to have to bleed system ?
5. Do you all agree that he has fitted the correct pump for our system ?, Grundfos Technical says he has. We have two rads downstairs and four upstairs .Pump is directly above boiler in kitchen, where it has been since house was built .He said a dumball valve has a floating ball inside it, rather like the ping pong ball in a snorkel valve. I have heard the sound of water travelling around other peoples systems, perhaps this is normal with a decent pump, advice guys please.

 

[PSH]

Just to update you all, Iwent around checking to see if any of the valves needed tightening ,and they were all tight except the one in the lounge ,which did do up about a half a turn. I noticed on its spindle before i did it up that it had a minute amount of water where the spindle met the nut ,but was drying before it had chance to run down the the valve body. I bled the top rad at the same time ,and since then we have not heard any air gurgling around the system. Maybe this is a coincidence and it just took a long time to bleed all the air out of the system I dont know. The sound of water rushing through the rads is still there though. All the rads are very hot still ,even though i have turned the boiler stat down to one and a half.

 

[bewsh]

The more the radiator valves are closed down/restricting the flow, the louder it'll be. try opening the valves a bit more to increase the flow to them, may quieten them down a bit.